Week 4 Reading - Chapter 4 and 5 PDF

Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 4.1 Sensation and Perception 1. Sensation vs. Perception Sensation: The process of detecting external stimuli (e.g., light, sound, touch) through sensory organs such as the eyes, ears, and skin. For example, when you see a tree, your eyes de...

Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 4.1 Sensation and Perception 1. Sensation vs. Perception Sensation: The process of detecting external stimuli (e.g., light, sound, touch) through sensory organs such as the eyes, ears, and skin. For example, when you see a tree, your eyes detect light waves reflected from the tree, which are then processed by photoreceptors in the retina. Perception: The brain’s interpretation and organization of sensory inputs into meaningful experiences. For instance, after light waves are detected by your eyes, your brain processes these signals and recognizes the object in front of you as a tree. Key Takeaway: Sensation refers to the detection of stimuli, while perception involves interpreting and organizing these stimuli to create an understanding of the world around us. 2. Signal Detection Theory Definition: Signal detection theory explains how we detect stimuli in environments where there is uncertainty or noise. It involves both sensory input and decision-making processes. Four Possible Outcomes: ○ Hit: Correctly detecting a stimulus that is present (e.g., hearing your phone ring when it actually rings). ○ Miss: Failing to detect a stimulus that is present (e.g., your phone rings, but you don’t hear it). ○ False Alarm: Detecting a stimulus that is not present (e.g., thinking you heard your phone ring when it didn’t). ○ Correct Rejection: Correctly identifying that no stimulus is present (e.g., realizing your phone didn’t ring and not perceiving any sound). Factors Influencing Detection Sensitivity: ○ Sensory Sensitivity: An individual's ability to detect weak stimuli depends on the sensitivity of their sensory organs and their psychological state. For example, when you’re anxious, you’re more likely to be hyper-aware of faint sounds. ○ Cognitive and Emotional Factors: Expectations, motivation, and arousal influence detection sensitivity. For instance, if you’re in a heightened state of alert, you may become more sensitive to noises you might otherwise ignore. Key Takeaway: Signal detection theory shows that perception is not solely based on the stimulus itself; it is influenced by decision-making, motivation, and sensory sensitivity. 3. Gestalt Principles of Perception Gestalt Psychology: This field explains how the brain naturally organizes sensory input into meaningful patterns or wholes, rather than processing individual elements separately. Key Gestalt Principles: ○ Proximity: Objects close together are perceived as a group. For example, dots arranged closely together are perceived as a cluster. ○ Similarity: Similar-looking objects are grouped together. In a mix of shapes, such as circles and squares, circles are grouped with circles and squares with squares. ○ Continuity: The brain prefers to perceive continuous patterns rather than disjointed segments. A wavy line crossing a straight line is perceived as two distinct lines. 1 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 ○ Closure: The brain fills in missing information to perceive a complete object. For example, even if parts of a circle are missing, your brain perceives the whole circle. ○ Figure-Ground Perception: This principle explains how we separate objects (figures) from their background (ground). For example, in the face-vase illusion, some people perceive a vase, while others see two faces in profile. Key Takeaway: Gestalt principles explain how the brain efficiently organizes sensory input by grouping and structuring what we perceive, making sense of complex stimuli. 4. From Sensation to Perception (Step-by-Step Process) 1. Sensation: Sensory receptors detect stimuli from the environment. For example, when you look at a tree, your eyes detect light waves reflecting off the tree. 2. Transduction: Sensory receptors convert physical stimuli into neural signals, which are sent to the brain. For example, photoreceptors in your eyes convert light waves into electrical signals for the brain to interpret. 3. Perception: The brain organizes and interprets the neural signals, creating a meaningful experience. For instance, your brain processes the electrical signals and recognizes the object in front of you as a tree. Key Takeaway: Sensation detects stimuli, transduction converts them into neural signals, and perception organizes these signals into meaningful experiences. All three steps are required for full perception of the world. 5. Transduction and Sensory Processing Transduction: The process of converting physical energy (e.g., light, sound, pressure) into neural impulses that the brain can interpret. This process is essential for perception because it allows the brain to process raw sensory input. Examples: ○ Vision: Photoreceptors in the retina convert light waves into electrical signals. ○ Hearing: Hair cells in the cochlea convert sound waves into neural signals. ○ Touch: Mechanoreceptors in the skin transduce pressure into neural impulses. Key Takeaway: Transduction is crucial for perception as it enables the brain to interpret sensory input in a meaningful way, allowing us to experience the world. 6. Sensory Adaptation Sensory Adaptation: A reduction in sensitivity to a constant stimulus over time, allowing the brain to focus on changes in the environment. Example: When you first enter a room with a strong odor, you immediately notice the smell. However, after a few minutes, the smell seems to fade because your brain has adapted to the constant stimulus. Key Takeaway: Sensory adaptation allows the brain to filter out unchanging stimuli and focus on new or changing information, enhancing processing efficiency. 2 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 7. Stimulus Thresholds Psychophysics: the field of tudy that explores how physical energy such as light and sound and their intsity relate to psychological experience. Absolute Threshold: The minimum amount of energy required for a stimulus to be detected at least 50% of the time. For example, the absolute threshold for hearing would be the lowest volume at which you can detect a sound half the time. Difference Threshold (Just Noticeable Difference - JND): The smallest detectable difference between two stimuli. Weber’s Law explains that the JND is proportional to the intensity of the original stimulus. For instance, you can easily detect a pinch of salt added to unsalted fries, but adding the same amount to already salty fries may not be noticeable. Key Takeaway: The stronger the original stimulus, the larger the change required to notice a difference, as explained by Weber’s Law. 8. Subliminal Messages and Perception Subliminal Messages: These are stimuli presented below the threshold of conscious awareness. While some believe that subliminal messages can influence behavior, research shows their effects are minimal. Example: In the 1980s, subliminal messages in a Judas Priest song were claimed to have caused two teenagers to attempt suicide, but scientific studies found no evidence supporting these claims. Key Takeaway: While subliminal messages may be detectable at an unconscious level, their actual impact on behavior is limited and often exaggerated in popular media. 9. Priming and Subliminal Perception Priming: A technique where previous exposure to a stimulus influences later responses. Subliminal priming involves presenting stimuli so quickly that they aren't consciously perceived, followed by a "mask" to prevent recognition. Research Example: Strahan et al. (2002) found that participants who were subliminally shown thirst-related words (e.g., "thirst" and "dry") rated drinks more positively if they were already thirsty. However, participants who were not thirsty were unaffected by these subliminal words. Key Takeaway: Subliminal priming can activate existing motivations, but it cannot create new ones. Its effects are often subtle and observable mainly under controlled laboratory conditions. 10. Top-Down and Bottom-Up Processing Top-Down Processing: This involves using prior knowledge, expectations, and experiences to interpret sensory information. For instance, when reading messy handwriting, your brain fills in the gaps based on your knowledge of language. Bottom-Up Processing: This is data-driven processing where perception builds from raw sensory input, without the influence of prior knowledge. For example, when encountering a completely new object, your brain processes sensory data to construct a perception from the ground up. Key Takeaway: Perception often involves both top-down and bottom-up processing. Prior knowledge and expectations (top-down) help us interpret ambiguous information, while bottom-up processing builds perception from the raw data we receive from our senses. 3 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 11. Attention and Perception Divided Attention: The ability to focus on multiple tasks at once, like texting while walking. However, research shows that divided attention reduces performance because the brain must constantly switch focus between tasks. Selective Attention: Focusing on one task or stimulus while ignoring others. For example, when watching a movie, you might tune out background noise to focus on the dialogue. Inattentional Blindness: This refers to the failure to notice unexpected stimuli when attention is directed elsewhere. This was famously demonstrated in the Gorilla Study (Simons & Chabris, 1999), where participants who focused on counting basketball passes completely missed a person in a gorilla suit walking across the screen. Practical Examples: ○ Witnesses to accidents may offer incomplete testimony because their attention was focused on something else. ○ Athletes may miss certain actions in a game because they’re concentrating on specific plays or movements. Anthony Barnhart’s Experiment: Barnhart used magic tricks to demonstrate inattentional blindness, showing how focus on one feature causes us to miss other important details. Key Takeaway: Attention is limited, and focusing intently on one aspect can lead to inattentional blindness, where obvious stimuli are missed. Example: Backward Messages in Music Backward Messages in Music: Some have claimed that backward messages in music (e.g., in the Beatles’ "Sgt. Pepper" album or Led Zeppelin’s "Stairway to Heaven") can influence behavior. However, scientific studies debunk these claims. Study Example: John Vokey and Don Read (1985) conducted a study where participants were asked to identify backward messages in music. Without prior instruction on what to listen for, participants were unable to detect meaningful messages. When they were told what to expect, they "detected" these messages, demonstrating the role of top-down processing—participants’ expectations shaped what they perceived. Key Takeaway: Belief in backward messages is a result of top-down processing. Without prior expectations or guidance, such messages remain undetected, showing that they don’t have unconscious influence over behavior. 4 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 4.2 The Visual System The Human Eye: Description: 1. The eye is a remarkable organ responsible for transforming physical light stimuli into neural impulses, which are then processed by the brain. This process enables us to perceive the world around us. 2. The eye must regulate the amount of light entering, focus on specific objects, and detect different wavelengths of light to ensure accurate visual perception. Functions: 1. Regulation of Light: The eye controls how much light enters to avoid overstimulation or underexposure. 2. Focusing Mechanism: Ensures objects at different distances are seen clearly. 3. Perception of Wavelengths: Different wavelengths correspond to different colors, and the eye can detect these changes. 4. Transformation to Action Potentials: Light is converted into action potentials, which carry visual information to the brain. How the Eye Gathers Light: Light: ○ In human perception, light refers to a narrow band of the electromagnetic spectrum. Although it encompasses a variety of wavelengths (like X-rays, ultraviolet rays, etc.), only visible light is detected by the human eye. ○ Function: Light travels in waves that vary in wavelength and amplitude, influencing the colors we see and the brightness of those colors. Wavelength: ○ The distance between the peaks of a wave. ○ Long Wavelengths: Correspond to reddish colors. ○ Short Wavelengths: Correspond to bluish colors. ○ Example: The variation in wavelengths allows humans to differentiate between colors. The ability to perceive color is likely an evolutionary trait aiding in distinguishing important objects like vegetation. Amplitude: ○ The height of the wave. ○ High Amplitude: Seen as bright colors. ○ Low Amplitude: Seen as dim colors. Electromagnetic Spectrum: ○ White light can be split into its component colors using a prism. ○ The visible spectrum is a small portion of the electromagnetic spectrum, sitting between ultraviolet (UV) and infrared (IR) rays. ○ Gamma Rays, X-Rays, and Ultraviolet Rays: Are not visible to the human eye but exist on the shorter wavelength side of the spectrum. ○ Radar, FM, TV Waves, and AC Circuits: Exist on the longer wavelength side but are also invisible. 5 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 Characteristics of Light: 1. Hue: ○ Refers to the color itself, determined by the wavelength of light. ○ Example: A red apple appears red because it reflects the wavelength corresponding to red. 2. Saturation: ○ Refers to the purity of the color. High saturation means vivid color, while low saturation makes a color look washed out. ○ Example: A freshly picked red apple has a more saturated hue compared to one left outside for a long period. 3. Intensity (Brightness): ○ Refers to how bright or dim a color appears, determined by the amplitude of the light wave. ○ Example: On a cloudy day, the color of objects appears less intense because of the lower brightness caused by the diffused light. Depth Perception: Our ability to perceive depth allows us to gauge distances and see the world in three dimensions. Binocular Cues: ○ Depth cues that require both eyes. ○ Binocular Disparity: Each eye sees a slightly different image due to the distance between them. The brain uses this difference to compute depth. Monocular Cues: ○ Depth cues that can be seen with just one eye. ○ Linear Perspective: Parallel lines (like a road) appear to converge as they get farther away, signaling depth. ○ Interposition: When one object blocks part of another, the blocked object is perceived as being farther away. Color Vision Theories: 1. Trichromatic Theory (Young-Helmholtz Theory): ○ Proposes that the retina contains three types of cones sensitive to different wavelengths: one for red, one for green, and one for blue. ○ The combination of activity across these three types of cones allows us to perceive a wide range of colors. ○ Example: When looking at a yellow object, both red and green cones are stimulated to create the perception of yellow. 2. Opponent-Process Theory: ○ Suggests that color perception is controlled by opposing pairs of colors: red-green, blue-yellow, and black-white. ○ These opponent processes explain why we can’t perceive a reddish-green or bluish-yellow simultaneously. ○ Example: Staring at a blue object for a long time and then looking at a white surface can result in seeing yellow as an afterimage due to the opponent-process system. 6 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 Visual Pathways (How Vision Works): 1. Light Detection: ○ Light enters the eye through the cornea, passes through the pupil, and is focused by the lens onto the retina. 2. Phototransduction: ○ In the retina, light is converted into neural signals by photoreceptor cells (rods and cones). 3. Neural Pathways: ○ These signals travel through the optic nerve to the visual cortex in the occipital lobe of the brain. 4. Perception: ○ The brain interprets these signals, allowing us to understand what we are seeing. Perception of Objects and Faces: Object Recognition: ○ The brain has specialized pathways for recognizing shapes and objects. ○ Top-Down Processing: We use our knowledge and expectations to interpret visual stimuli. Face Recognition: ○ Specialized areas of the brain (such as the fusiform face area) are responsible for recognizing faces. ○ Damage to these areas can lead to conditions such as prosopagnosia (face blindness), where individuals cannot recognize faces even though they can see other objects clearly. The Structure of the Eye: Sclera: ○ Definition: The white, outer layer of the eye. ○ Function: Provides structural support and protection to the eye. Cornea: ○ Definition: The transparent front part of the eye. ○ Function: Bends (refracts) light as it enters the eye to help focus it on the retina. Pupil: ○ Definition: The black circular opening in the center of the iris. ○ Function: Controls the amount of light entering the eye by changing its size. Dilation: The pupil expands to allow more light into the eye. Constriction: The pupil shrinks to limit the amount of light. Iris: ○ Definition: The colored part of the eye surrounding the pupil. ○ Function: Contains muscles that adjust the size of the pupil to regulate light intake. The iris also gives the eye its characteristic color. Lens: ○ Definition: A transparent structure behind the pupil. ○ Function: Changes shape to focus light onto the retina. This focusing process is called accommodation. Accommodation: ○ Definition: The process by which the lens changes shape to focus light onto the retina, ensuring a clear image. 7 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 ○ Example: When you look at something far away, the lens becomes flatter, and when you look at something up close, the lens becomes rounder. Retina: ○ Definition: The light-sensitive layer at the back of the eye. ○ Function: Contains photoreceptors that convert light into neural signals, which are sent to the brain for interpretation. The Retina: From Light to Nerve Impulse: Rods: ○ Definition: Photoreceptors that occupy peripheral regions of the retina, sensitive under low-light conditions, and primarily detect black, white, and shades of gray. ○ Example: In a dark room, rods help you detect movement and shapes but not colors. Cones: ○ Definition: Photoreceptors concentrated around the fovea, responsible for detecting color and fine detail. ○ Example: In a well-lit environment, cones allow you to see in color and pick up on detailed features of objects. Dark Adaptation: ○ Definition: The process by which rods and cones become more sensitive to light after being in the dark for a period of time. ○ Function: After you enter a dark room, you gradually become better at seeing in the low-light environment as your rods become more sensitive. ○ Example: When you walk into a dark movie theater, it initially seems completely dark, but after a few minutes, your vision improves due to dark adaptation. Distribution of Rods and Cones: ○ Rods are more concentrated in the peripheral parts of the retina, which is why your peripheral vision is better at detecting movement in dim lighting. ○ Cones are concentrated in the fovea, which is responsible for sharp, central vision and color detection. Common Visual Disorders: 1. Color Blindness: Definition: A condition in which individuals have difficulty distinguishing certain colors, particularly red and green. Cause: Color blindness occurs when cones in the retina do not have the correct proteins to detect specific wavelengths of light. Red-green color blindness: In most cases, cones sensitive to green or red lack the correct proteins. Origin: Most forms of color blindness are genetic. 2. Nearsightedness (Myopia): Definition: A condition where individuals can see objects close to them but have difficulty focusing on objects farther away. Cause: The eyeball is slightly elongated, causing images to focus in front of the retina instead of directly on it. Correction: Can be corrected with glasses, contact lenses, or LASIK surgery to properly focus light onto the retina. 8 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 3. Farsightedness (Hyperopia): Definition: A condition where individuals can see distant objects clearly but struggle to focus on nearby objects. Cause: The eyeball is shorter than normal, causing images to focus behind the retina. Correction: Corrected with glasses, contact lenses, or LASIK surgery to ensure light focuses correctly on the retina. 4. Astigmatism: Definition: A condition where the cornea is irregularly shaped, causing blurred or distorted vision. Cause: Light does not focus properly on the retina because of an uneven corneal shape. Correction: Can be treated with glasses, contact lenses, or refractive surgery, such as LASIK. 5. LASIK Surgery: Procedure: LASIK (Laser-Assisted In Situ Keratomileusis) is a surgical procedure used to correct nearsightedness, farsightedness, or astigmatism. Steps: 1. Surgeons create a small flap on the surface of the cornea. 2. A laser is used to reshape the cornea so that light focuses properly on the retina. 3. The flap is repositioned, and healing occurs naturally within a few days. For Nearsighted Patients: The cornea is flattened. For Farsighted Patients: The cornea is made steeper. Success: Approximately 90% of patients report satisfaction with the results. Visual Perception and the Brain: 1. Optic Nerve and Optic Chiasm: ○ Optic Nerve: Transmits visual information from the retina to the brain. ○ Optic Chiasm: The point where the optic nerves cross at the midline of the brain. Information from the left visual field is processed by the right hemisphere of the brain, and vice versa. This arrangement allows visual information to be processed efficiently and helps ensure that some visual abilities are preserved if part of the brain is damaged. 2. Visual Cortex: ○ Primary Destination: The visual cortex, located in the occipital lobe, is the brain's primary center for processing visual information. ○ Thalamus: The optic nerve first connects with the thalamus, the brain’s "sensory relay station," which sends the information to the visual cortex. ○ Lateral Geniculate Nucleus: A specialized region in the thalamus responsible for processing visual information before it reaches the cortex. Feature Detection Cells: Definition: Specialized cells in the visual cortex that respond to specific features of a stimulus, such as edges, angles, and movement. Function: These cells help break down visual input into distinct components for further processing in the brain. ○ Hubel & Wiesel: The researchers who first discovered feature detection cells in the visual cortex. 9 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 The Two Streams of Vision: 1. Dorsal Stream (where): ○ Definition: A visual processing pathway that extends from the occipital lobe to the parietal lobe. It is primarily responsible for determining where an object is in space and for guiding movements related to that object. ○ Function: Primarily responsible for processing the "where" aspects of visual stimuli, including spatial location and movement. ○ Example: Reaching for a cup on a table involves the dorsal stream to determine the location of the cup and guide the hand toward it. 2. Ventral Stream (what): ○ Definition: A pathway that extends from the visual cortex to the lower part of the temporal lobe. ○ Function: Responsible for object recognition, identifying "what" an object is. ○ Impairments: Damage to the ventral stream can lead to difficulty recognizing objects, despite normal visual acuity. Research Example (Patient D.F.): D.F. suffered damage to the ventral stream (responsible for object recognition) but could still interact with objects. She was able to post a letter into a mailbox slot even though she couldn't recognize or name the letter. This demonstrates that the dorsal stream was intact and could guide her motor actions based on the spatial positioning of the object. Are Faces Special? 1. Face Perception: ○ Importance of Faces: Faces provide a wealth of social information beyond mere identification. For example, we can infer someone's emotional state from their facial expressions. This emotional and social context makes faces distinct and highly important in terms of how the brain processes them. ○ Figure 4.21 (Seeing Faces): Example: The Italian artist Giuseppe Arcimboldo created a painting where vegetables form the shape of a human face. When viewing the image, most people can clearly identify the "face," even though it is composed of non-facial objects (vegetables). This shows that our brains are wired to detect facial patterns, even when they are abstract or inverted. 2. How Does the Brain Process Faces? ○ Face Blindness (Prosopagnosia): Definition: A condition where individuals lose the ability to recognize faces, though they can still recognize voices and other identifying characteristics. Cause: This condition is linked to damage in the fusiform face area (FFA) of the brain, located in the lower part of the right temporal lobe. ○ Fusiform Face Area (FFA): Definition: A specific region in the brain responsible for face perception. Function: This area shows increased activity when we view faces compared to other stimuli. Faces are processed holistically, meaning that we perceive the whole face rather than individual features like the nose, eyes, or mouth. 10 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 ○ Inverted Faces: The brain processes inverted faces differently from upright faces. When faces are upside down, the FFA shows much less activity, and individuals often struggle to recognize specific facial features. Perceptual Constancy: Definition: The ability to perceive objects as having constant size, shape, and color despite changes in perspective or lighting. Types of Perceptual Constancy: 1. Shape Constancy: We perceive an object’s shape as constant even if its retinal image changes due to viewing angle. Example: A door appears rectangular to us, even though its shape may look distorted when viewed at different angles. 2. Size Constancy: Objects are perceived to have the same size despite changes in distance. Example: A person walking away still appears the same size, even though their image on the retina shrinks. 3. Color Constancy: The ability to perceive colors consistently, even when the lighting changes. Example: A red car looks red whether it is in bright sunlight or shade. Depth Perception Binocular Depth Cues: 1. Binocular depth cues rely on both eyes working together. These cues include: Convergence: The closer an object, the more your eyes need to converge (move inward) to focus on it. Retinal Disparity: The slight difference in images between your two eyes. Your brain uses this disparity to perceive depth. Monocular Depth Cues: 1. Monocular cues can be observed with just one eye and are critical for depth perception in both real-world and two-dimensional (flat) images. 2. Accommodation: The process by which the eye lens changes shape to focus on objects at different distances. When focusing on a nearby object, the lens becomes thicker, and the brain uses feedback from this process to estimate depth. 3. Motion Parallax: A depth cue that occurs when you or your surroundings are in motion. Closer objects seem to move faster than distant objects. Example: Looking out of a car window, trees close to the road zoom by quickly, while distant mountains barely seem to move. Pictorial Depth Cues: 1. These are the techniques used by artists to give a sense of depth in two-dimensional images like paintings, drawings, and photos. Let's break these down with examples. 2. Linear Perspective: Definition: This cue involves parallel lines (such as roads, train tracks) appearing to converge as they recede into the distance. The farther they go, the closer together they seem to get, eventually meeting at a vanishing point. 11 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 Example: In Gustave Caillebotte’s painting (Figure 4.27), "Paris, a Rainy Day," the lines of the street and buildings narrow toward a point in the background, giving the illusion of distance. 3. Interposition (Occlusion): Definition: When one object partially blocks the view of another, the blocked object is perceived as being farther away. Example: In a scene where a person is standing in front of a car, and the car is only partially visible, you perceive the person as being closer to you than the car. 4. Light and Shadow: Definition: Light and shadow provide depth cues by showing how light affects the perception of objects. Shadows cast by objects help indicate the object’s position in space. Example: A ball casting a shadow on the ground indicates it is above the ground. The way the light falls on the object also highlights its three-dimensionality. 5. Texture Gradient: Definition: The gradual reduction of texture detail as an object recedes into the distance. Objects closer to the viewer appear more detailed, while those farther away appear blurrier and less distinct. Example: In a photo of a field of flowers, the flowers in the foreground appear sharp and detailed, but those in the distance appear as a blend of colors without distinct shapes. 6. Relative Size: Definition: When two objects are known to be the same size, the one that appears smaller is perceived as being farther away. Example: Two apples of the same size are placed at different distances from the observer. The apple that looks smaller is assumed to be farther away. 7. Height in Plane: Definition: Objects placed higher in the visual field (closer to the horizon line) are perceived as being farther away. Example: In a landscape painting, mountains that are higher up in the painting appear farther away than objects lower in the frame, like trees or buildings. Artistic Applications of Depth Perception: The Artist’s Studio Example (Rembrandt): ○ Rembrandt manipulated viewer's eye movements by using areas of high detail and contrast to guide attention. The more detailed regions attract the viewer’s gaze first, creating a sense of three-dimensional space on a flat canvas. Figure 4.27 (Gustave Caillebotte's Painting "Paris, a Rainy Day"): ○ This painting uses linear perspective, texture gradient, and relative size to create depth. The streets narrow as they recede into the distance, and the buildings and pedestrians shrink, giving the impression of a three-dimensional cityscape. Figure 4.28 (The Corridor Illusion): ○ The illusion shows how linear perspective and height in plane can affect perception. Two identical objects placed at different points in the corridor appear to be of different sizes because of their positions in the visual field. 12 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 Other Key Concepts: The Corridor Illusion: ○ Objects at the “back” of the drawing appear larger than those in the foreground, even though they are the same size. This demonstrates how depth cues like linear perspective can trick our brains into misjudging the size of objects based on their placement in a visual scene. Harvard Neurobiologists on Rembrandt: ○ There is speculation that Rembrandt may have suffered from stereo blindness (an inability to see binocular images). He would therefore have relied on monocular cues, such as light and shadow and relative size, to depict depth in his paintings. 13 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 5.1 Biological Rhythms of Consciousness: Wakefulness and Sleep Franz Kafka Example Franz Kafka (1883–1924) often wrote about surreal situations like in The Metamorphosis, where a man turns into an insect. Kafka's own struggles with sleep deprivation and insomnia may have influenced his works. Kafka often referred to sleep deprivation as giving access to strange thoughts, but it also affected his physical and mental health. This module explores how sleep deprivation and sleep disorders like Kafka's affect behavior. What is Consciousness? Consciousness refers to a person's subjective awareness, including thoughts, perceptions, experiences, and self-awareness. It is the "you" in your moment-to-moment existence. This module looks at consciousness in terms of two key elements: ○ Wakefulness: Refers to whether a person is awake or asleep. ○ Awareness: Refers to whether a person understands their thoughts and surroundings. Levels of Consciousness (Fig. 5.1): Conscious wakefulness: Full awareness and alertness. Drowsiness: Reduced alertness before sleep. Light Sleep: The initial stages of sleep when awareness begins to fade. Deep Sleep: Minimal awareness, during which the body enters a restorative phase. REM Sleep: Dreaming occurs here, and the person is somewhat aware. Vegetative State: The person is awake but without awareness. Coma/Anesthesia: The person lacks both wakefulness and awareness. What is Sleep? Sleep is a significant part of life, as humans spend approximately one-third of their lives sleeping. Key questions explored in this module include: ○ Why do we need sleep? ○ Why do we dream? ○ What is sleep, and how does it relate to biological rhythms? Biological Rhythms Biological Rhythms: Patterns that occur within days, weeks, months, or years. These rhythms are linked to cycles in the environment, such as the transition between day and night or seasons. Example: Bears hibernating is an example of a circannual rhythm, which refers to biological rhythms occurring on a yearly basis. Infradian Rhythms: These rhythms last longer than a day. For example, the menstrual cycle is an infradian rhythm. Ultradian Rhythms: Rhythms that occur more frequently than once a day, such as the regulation of heart rate, urination, and some hormonal activity. 14 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 Circadian Rhythms Circadian rhythms: Internally driven daily cycles of approximately 24 hours, which regulate physiological and behavioral processes like sleep, hunger, and alertness. For example, you might feel most awake in the morning and sleepy at night due to your circadian rhythm. The Suprachiasmatic nucleus (SCN), located in the hypothalamus of the brain, plays a crucial role in controlling these rhythms by responding to light. The SCN adjusts the body’s melatonin levels to signal wakefulness and sleep. ○ Melatonin: A hormone secreted by the pineal gland that regulates sleep-wake cycles. ○ Light exposure triggers the SCN to reduce melatonin levels, which helps promote wakefulness during daylight. Exposure to artificial light, such as from smartphones, can disrupt circadian rhythms by interfering with the SCN’s control of melatonin, making it harder to fall asleep. Endogenous Rhythms Not all biological rhythms are influenced by external factors. Endogenous rhythms are biological rhythms that are generated from within the body, independent of external cues like light, temperature, or time of day. Studying these rhythms is challenging because it requires isolating subjects from all external time cues. For example, researchers in the 1960s and 1970s had participants spend extended periods in caves to study the effect of isolation on biological rhythms. ○ Participants often adopted a slightly longer daily rhythm, closer to 25 hours, without the influence of external cues like sunlight. Changes in Biological Rhythms across the Lifespan Although the sleep-wake cycle, part of our circadian rhythms: internal biological processes that follow a roughly 24-hour cycle, such as the sleep-wake cycle. ○ Remains close to 24 hours throughout life, some patterns change with age. REM sleep (Rapid Eye Movement sleep): a stage of sleep characterized by rapid eye movements, vivid dreams, and brain activity similar to being awake. Decreases as we move from infancy and childhood into adulthood. This reduction in REM sleep is linked to the formation of new synapses and the growth of myelin on neurons (Cao et al., 2020). People’s chronotype—the natural tendency to prefer sleeping earlier or later in a 24-hour period—also changes with age: ○ During teenage years and early adulthood, many individuals become night owls, preferring to stay up late and sleep in. This shift can make early school hours challenging. ○ As adults age, they tend to prefer going to bed and waking up earlier, and many elderly individuals become early risers. Research Findings: Adolescents who prefer staying up late often report feeling sleepier and struggle more with emotional regulation during early school hours, especially when school starts before 9:00 a.m. (Owens et al., 2016). Older adults (aged 60–80) tend to perform better in cognitive tests in the morning rather than later in the day. When tested later, they show greater difficulty separating new information from old and exhibit more variability in reaction times (Hasher et al., 2002; Hogan et al., 2009). These findings suggest that older adults are naturally more alert in the morning. 15 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 The Stages of Sleep Sleep is divided into distinct stages, each characterized by unique EEG (electroencephalogram) signals, which measure electrical activity in the brain. These signals help track brain activity during different phases of sleep. ○ EEG (Electroencephalogram): A tool used to measure brain activity, particularly during different stages of sleep. The Four Main Stages of Sleep: 1. Stage 1: This is the lightest stage of sleep, where the brain produces slower waves known as theta waves. It’s easy to awaken someone in this stage, which lasts about 5–10 minutes. 2. Stage 2: During this stage, body temperature decreases, heart rate slows, and breathing becomes more regular. Brain activity slows, but there are occasional bursts of rapid brain activity called sleep spindles, which are believed to play a role in memory consolidation. This stage typically lasts around 10–25 minutes. 3. Stage 3: Also called deep sleep or slow-wave sleep, this stage is marked by the presence of delta waves, which are large, slow brain waves. This is the most restorative sleep stage, during which the body repairs and regenerates tissues, builds bone and muscle, and strengthens the immune system. It lasts about 20–40 minutes. 4. Stage 4: This stage is very similar to Stage 3, and together they are referred to as slow-wave sleep. Waking someone from this stage is difficult, and if woken, they will feel groggy and disoriented. After progressing through these stages, the body cycles back through the lighter stages of sleep before entering REM sleep: REM sleep: In this stage, brain activity is similar to wakefulness, and it is when most vivid dreams occur. The body experiences atonia (temporary paralysis), except for the eyes and breathing muscles. REM periods become longer as the night progresses, and the average sleep cycle (including REM and non-REM stages) lasts about 90–120 minutes. EEG Signals and Sleep Stages: During Stage 1, EEG signals show slower waves. As the sleeper progresses into Stage 3 and Stage 4, the brain produces delta waves: slow, large brain waves characteristic for deep sleep and essential for body restoration In REM sleep, brain activity resembles wakefulness, and the EEG shows fast, random waves similar to when someone is awake. Sleep Requirements Change with Age (Fig. 5.3) The amount of sleep required decreases with age: ○ Infants need the most sleep, often up to 16 hours a day, primarily in REM sleep. ○ Teenagers generally need around 9 hours of sleep but often get less due to social and academic pressures. ○ Adults typically need 7–9 hours of sleep per night. ○ Older adults (60+ years) usually need slightly less sleep, around 6–7 hours, and may experience more fragmented sleep. 16 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 Order and Duration of Sleep Stages (Fig. 5.5) The sleep cycle is organized in a predictable pattern. After falling asleep, the body progresses through the various non-REM sleep stages, moving from light to deep sleep, followed by a period of REM sleep. ○ Each sleep cycle lasts approximately 90–120 minutes. ○ Early in the night, the body spends more time in deep sleep (Stages 3 and 4). ○ As the night progresses, REM sleep periods become longer, and deep sleep stages become shorter. Why Do We Need Sleep? Sleep is such a natural part of life that it's difficult to imagine a world without it. A critical question explored in sleep research is: Why do humans and animals need to sleep in the first place? Theories of Sleep 1. Restore and Repair Hypothesis: ○ The most intuitive explanation for sleep is the restore and repair hypothesis—the idea that the body needs sleep to restore energy levels and repair any wear and tear experienced during daily activities. ○ Research on sleep deprivation shows that sleep is not merely restful but essential for physical and psychological well-being. A lack of sleep can lead to cognitive decline, emotional disturbances, and even impaired immune function (Born et al., 1997). ○ During sleep, the brain clears waste products such as β-amyloid proteins. This process occurs as cerebrospinal fluid pulses in and out of the brain, washing away waste products (Fultz et al., 2019; Xie et al., 2013). Without this, harmful waste builds up, potentially leading to neurodegenerative diseases like Alzheimer's. 2. Preserve and Protect Hypothesis: ○ The preserve and protect hypothesis proposes that sleep has two evolutionary functions: conserving energy and protecting organisms from danger. ○ For example, predator-prey dynamics influence sleep patterns. Animals most vulnerable to predators sleep in shorter periods and in safer environments, while predators like lions can afford to sleep up to 15 hours a day. ○ Humans, being diurnal and reliant on vision, evolved to sleep at night when they are at a disadvantage compared to nocturnal predators (Siegel, 1995). This theory highlights how the timing and duration of sleep across species are shaped by evolutionary pressures. Both theories contribute to the understanding of sleep's dual purpose: restoration and protection. The need for sleep varies across species, balancing the demands of biological restoration and survival. Sleep Deprivation and Sleep Displacement Sleep deprivation occurs when an individual consistently does not get enough sleep. It leads to impaired cognitive functions, poor decision-making, and emotional instability. Sleep deprivation can also be caused by sleep displacement, which happens when sleep patterns are disrupted by external factors such as jet lag or daylight saving time shifts. 17 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 Effects of Daylight Saving Time (DST): Studies have shown that when the clock shifts forward for spring DST, people lose an average of 40 minutes of sleep. This loss of sleep has significant consequences: ○ A study found a spike in car accidents immediately after the time change, particularly in the spring shift. This highlights the widespread negative impact that even a small amount of sleep loss can have (Smith, 2016). ○ Figure 5.6 shows an increase in car accidents following the spring shift, as compared to the fall shift, where people gain an hour of sleep. Jet Lag: Jet lag occurs when a person travels across multiple time zones, disrupting their circadian rhythms. The body's internal clock struggles to adjust to the new time zone, leading to symptoms such as fatigue, irritability, and impaired concentration. ○ Figure 5.7 shows how it is generally easier to adjust when traveling eastward because the body has to shorten its day. Traveling westward requires lengthening the day, making it harder to adjust. ○ Jet lag can be alleviated by gradually adjusting sleep schedules before travel or by using light exposure to reset the body’s circadian rhythms. Consequences of Sleep Deprivation 1. Physical and Cognitive Impairments: ○ Sleep deprivation can have similar effects on the brain as being intoxicated. For example, going 24 hours without sleep can impair cognitive performance as much as having a blood alcohol concentration of 0.10% (Pilcher & Huffcutt, 1996). ○ Sleep inertia, or grogginess upon waking, is exacerbated by sleep deprivation, making it harder to perform even simple tasks (Tassi & Muzet, 2000). 2. Emotional and Psychological Effects: ○ Sleep deprivation negatively affects emotional regulation, making people more likely to experience mood swings and increased irritability. It also heightens stress levels, anxiety, and emotional instability. 3. Long-term Health Effects: ○ Chronic sleep deprivation is linked to serious health conditions such as obesity, diabetes, cardiovascular disease, and weakened immune function. ○ Adolescents who are sleep-deprived tend to exhibit poorer academic performance, increased risk of depression, and even substance abuse (Dewald et al., 2010). Sleep Deprivation and Sleep Displacement Sleep deprivation refers to not getting enough sleep over a period of time, which leads to various impairments in cognitive, emotional, and physical functioning. People suffering from sleep deprivation can experience symptoms like impaired memory, poor decision-making, and slower reaction times. In fact, staying awake for 24 hours can impair performance similarly to having a blood alcohol concentration of 0.10% (Pilcher & Huffcutt, 1996). 18 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 Sleep displacement occurs when sleep schedules are shifted or interrupted. This can be caused by external factors such as jet lag or daylight saving time (DST) changes. Displacement of sleep can have significant effects on both personal health and public safety. Daylight Saving Time (DST) Impact: The switch to DST, particularly the spring shift, results in the loss of an hour of sleep, with the average person losing around 40 minutes of sleep. This sleep loss can affect alertness and lead to a higher risk of accidents. Research has found that there is a noticeable increase in car accidents following the spring time change, as shown in Figure 5.6. Jet Lag: Jet lag occurs when a person crosses multiple time zones, disrupting their internal circadian rhythms (the body's internal clock that regulates the sleep-wake cycle). Jet lag symptoms include fatigue, irritability, and difficulty concentrating. Adjusting to new time zones can be challenging, especially when traveling westward, which requires lengthening the day. Eastward travel, which requires shortening the day, is typically easier to adjust to (as shown in Figure 5.7). To mitigate jet lag, travelers are advised to gradually adjust their sleep schedule before departure and use light exposure to help reset their body clock in the new time zone. Effects of Sleep Deprivation: 1. Cognitive Effects: ○ Sleep deprivation significantly impairs cognitive abilities, such as decision-making and memory retention. For example, people experiencing sleep deprivation perform worse on tasks involving critical thinking and decision-making, as their brain processes information less efficiently. 2. Physical and Emotional Consequences: ○ Chronic sleep deprivation is linked to long-term health problems, including cardiovascular disease, obesity, and a weakened immune system. Sleep-deprived individuals also show higher levels of stress and are more prone to mood swings and anxiety. 3. Sleep Inertia: ○ Sleep inertia refers to the grogginess and disorientation experienced immediately after waking up, especially from deep sleep stages. This can be more severe when a person is sleep-deprived and can impair performance on tasks that require immediate attention. Theories of Dreaming Dreaming is an integral aspect of sleep, although its purpose remains unclear. Various studies have attempted to understand the content of dreams. For example, a study involving 1348 Canadian university students found that dreams could be categorized into 16 distinct groups using factor analysis, a statistical method that helps identify patterns in data. Females in the study tended to report more negative dreams related to themes like failure, loss of control, and frightening animals, while males had more dreams related to magical abilities and alien encounters (Nielsen et al., 2003). 19 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 The Psychoanalytic Approach (Freud’s Theory) Sigmund Freud proposed one of the earliest and most influential theories of dreaming in his work The Interpretation of Dreams (1899). Freud argued that dreams are a form of wish fulfillment, where the unconscious mind expresses repressed desires that are typically related to primal urges, particularly involving sex and aggression. ○ In waking life, humans suppress these desires because acting on them would be socially unacceptable. However, during sleep, the conscious mind relaxes its control, allowing the unconscious mind to express these hidden desires. Freud's Dream Content: Freud divided dreams into two types of content: ○ Manifest content: This is the literal imagery and storyline of the dream. For example, if you dream about climbing a mountain, that is the manifest content of the dream. ○ Latent content: This refers to the hidden, symbolic meaning behind the manifest content. Freud believed that the latent content of dreams often represents repressed desires or emotions, typically of a sexual or aggressive nature. In Freud's theory, the act of climbing the mountain might symbolize overcoming personal challenges or striving for power. Freud’s ideas have had a lasting impact on how people interpret dreams, though his theories have faced significant criticism in modern psychology. One of the main critiques is that Freud’s theories are difficult to test scientifically because they cannot be falsified, meaning there is no way to prove or disprove them. While Freud's work requires subjective interpretation of dreams, the scientific support for his theories remains limited. Much of Freud's dream analysis relies on symbolic meanings, which can vary greatly depending on the interpreter’s perspective. As a result, modern research has largely moved away from Freudian interpretations, focusing instead on more empirical approaches to understanding dreams. The Problem-Solving Theory The problem-solving theory of dreaming, proposed by Rosalind Cartwright, suggests that the thoughts and concerns we have while awake carry over into our dreams. This theory posits that dreams may serve a function in helping us solve problems we encounter during our waking hours (Cartwright et al., 2006; Webb & Cartwright, 1978). According to this theory, many of the images and thoughts we experience during dreams are relevant to the challenges we face in our daily lives. For example, individuals in poor physical health tend to have more dreams about pain, injuries, or medical issues (King & DeCicco, 2007). While this theory highlights the connection between daily concerns and dreams, it doesn’t explain the specific cognitive mechanisms influenced by dreaming. Modern dream research tends to focus on the biological activity of dreaming, especially during REM sleep, when dreams are most vivid and complex. The Activation-Synthesis Hypothesis The activation-synthesis hypothesis suggests that dreams are a byproduct of brain activity during sleep, particularly REM sleep. This theory was first proposed by Hobson and McCarley (1977), who argued that dreams arise from bursts of excitatory messages from the pons (a part of the brainstem). 20 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 ○ The pons sends signals to different areas of the brain, stimulating the occipital lobe and temporal lobe, which produce the visual and auditory imagery that we often associate with dreams. These regions of the brain generate imaginary sights and sounds. ○ The activation part of the model refers to the random bursts of neural activity during REM sleep, while the synthesis part refers to the brain’s attempt to create a coherent narrative from these random signals. The frontal lobes, which are responsible for organizing thoughts and forming narratives, attempt to turn this chaotic brain activity into a structured dream. This process is like receiving random words and trying to arrange them into a meaningful sentence (Hobson et al., 2000). Figure 5.8: The Activation-Synthesis Hypothesis of Dreaming This figure illustrates how the pons sends excitatory messages through the thalamus to the sensory and emotional areas of the cortex. These signals generate the visual and emotional imagery of dreams. Inhibitory signals from the pons also prevent physical movement during dreaming by sending signals to the spinal cord. Working the Scientific Literacy Model: Dreams, REM Sleep, and Learning The activation-synthesis hypothesis also has implications for learning and memory. If the brain can impose structure on random signals during REM sleep, it may be able to use this process to organize and restructure information learned during the day. Research suggests that approximately 20–25% of total sleep is spent in REM sleep. When deprived of REM sleep, people often experience REM rebound, which is when the brain spends more time in REM sleep than usual to make up for lost time (Aserinsky & Kleitman, 1953). During REM sleep, the brain produces brainwaves similar to wakefulness, even though the body remains at rest. This similarity suggests that the processes during REM sleep may be similar to those occurring while awake, including memory consolidation and emotional regulation (Born et al., 2012). The Role of REM Sleep in Learning Studies have demonstrated that REM sleep helps with memory consolidation and problem-solving. For example, one study found that students who were deprived of REM sleep after learning a task had more difficulty retaining the information (Smith, 1993). REM sleep also appears to play a key role in problem-solving. When deprived of REM sleep, individuals struggle to complete tasks that require creative thinking or forming new associations (Stickgold et al., 1999; Walker et al., 2002). REM sleep is not just about dreaming but also helps the brain link together new information and previously learned material, supporting the formation of new memories. Why Does REM Sleep Matter for Learning? Studies suggest that REM sleep helps the brain beyond simply restoring physical energy. REM sleep enhances the brain’s ability to learn new tasks and consolidate new information. ○ For instance, research has found that students who were tested on complex learning tasks after being deprived of REM sleep performed worse than those who got a full night’s sleep. This suggests that REM sleep plays a critical role in cognitive functioning, especially when it comes to retaining newly learned information. 21 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 Interestingly, research has shown that the final REM periods during the night are particularly important for learning. These periods, which occur early in the morning, seem to be the most beneficial for tasks involving memory and problem-solving (Smith, 2001). The connection between REM sleep and learning emphasizes the importance of consistent, uninterrupted sleep. Even though many students and professionals function on limited sleep, this research highlights how crucial REM sleep is for effective learning and memory. Disorders and Problems with Sleep Throughout this module, we've learned that sleep is a crucial biological and psychological process. Without enough sleep, individuals are vulnerable to cognitive, emotional, and physical symptoms. Because sleep is so important for overall health and well-being, a significant amount of research has focused on diagnosing and treating sleep disorders. The following section discusses some of the more common sleep disorders. Insomnia Insomnia is the most widely recognized sleep disorder, characterized by an extreme lack of sleep. According to the Canadian Community Health Survey from Statistics Canada, about 24% of Canadian adults (approximately 9 million people) suffer from insomnia (Chaput et al., 2018). Insomnia isn't simply about not getting enough sleep, as people’s sleep needs differ. It is defined by the degree to which lack of sleep affects daily functioning (e.g., school, work, or social life). To qualify as a sleep disorder, insomnia must persist for at least three months. Types of Insomnia: Onset insomnia: Difficulty falling asleep, usually taking more than 30 minutes to do so. Maintenance insomnia: Trouble staying asleep throughout the night or waking up frequently. Terminal insomnia (early morning insomnia): Waking up too early and being unable to return to sleep (Pallesen et al., 2001). Insomnia can also be secondary, meaning it arises as part of another issue such as depression, pain, or other medical conditions like ADHD (Attention Deficit Hyperactivity Disorder). Secondary insomnia can also be caused by certain medications (Corkum et al., 2014). When insomnia is the primary symptom, it is labeled as insomnia disorder. Insomnia may not seem as serious as other sleep disorders, but it significantly affects people’s ability to function in daily life. Nightmares and Night Terrors While most dreams are ordinary or even pleasant, nightmares are dreams that are disturbing or frightening, and they often occur during REM sleep (Levin & Nielsen, 2007). ○ Nightmares can be emotionally intense, sometimes causing people to wake up in distress. Many adults (85%–95%) have experienced nightmares with negative emotional content such as feelings of fear, sadness, or anger (Levin, 1994; Schredl, 2003). ○ Nightmares are often linked to psychological conditions such as anxiety and emotional reactivity. Studies show that nightmares are more common in people with depression and anxiety disorders and are more prevalent in females (Nielsen et al., 2006), who tend to report higher levels of these conditions. 22 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 ○ The "synthesis" part of dreaming during nightmares may work to organize negative emotional experiences, making nightmares more common during periods of heightened stress or anxiety. Night Terrors: Unlike nightmares, night terrors are not considered dreams but are intense episodes of panic and arousal that occur during NREM sleep. Night terrors affect about 1% to 6% of children and 1% of adults (Kales et al., 1980). ○ During a night terror, individuals may scream, fight back against imaginary attackers, or try to escape from danger. The individual often has no recollection of the event after waking up, unlike with nightmares (Szelenberger et al., 2005). ○ Night terrors typically occur during stressful periods in life, such as when parents are separating or during major transitions. They may be linked to feelings of anxiety. Treatment options often include counseling to manage underlying stress and anxiety. Movement Disturbances During REM sleep, the brain typically sends inhibitory signals to the spinal cord to prevent movement. This mechanism ensures that while dreaming, people do not physically act out their dreams. However, in some cases, this inhibition fails, leading to REM behavior disorder. REM Behavior Disorder: REM behavior disorder occurs when individuals appear to be physically acting out their dreams. This can include movements such as fighting, kicking, or other dream-related actions, often leading to self-harm or harm to others (Schenck & Mahowald, 2002). Treatment for REM behavior disorder includes medications like benzodiazepines, which help inhibit the central nervous system (Paparrigopoulos, 2005). Sleepwalking (Somnambulism): Somnambulism, or sleepwalking, is another movement disorder that occurs during NREM sleep, specifically stages 3 and 4. It involves wandering or performing other activities while asleep, and sleepwalkers typically do not remember the episode. ○ Unlike REM behavior disorder, sleepwalking cannot be treated with medication. The best approach is to ensure that the sleepwalker’s environment is safe, minimizing the risk of injury. Sexsomnia: Sexsomnia, or sleep sex, is a rare disorder in which individuals engage in sexual activity during sleep without conscious awareness. Cases of sexsomnia can range from touching oneself to more extreme behaviors, including sexual encounters with others. Although it may seem like a joke, sexsomnia can have serious legal and personal consequences (Béjot et al., 2010). 23 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 Sleep Apnea Sleep apnea is a disorder characterized by the temporary inability to breathe during sleep. It is most common in overweight or obese individuals, and it is roughly twice as prevalent in men as in women (Lin et al., 2008). ○ In most cases of sleep apnea, the airway becomes obstructed, leading to snoring, gasping for air, and poor sleep quality. Treatment Options: Treatment for mild sleep apnea includes using dental devices to hold the mouth in a specific position or using a continuous positive airway pressure (CPAP) machine to keep the airway open with increased air pressure (McDaid et al., 2009). Figure 5.9 illustrates how the airway becomes obstructed in sleep apnea, reducing airflow and disrupting the sleep cycle. Effects of Sleep Apnea: Sleep apnea not only disrupts sleep but can also lead to cognitive impairments due to reduced oxygen flow. Individuals with untreated sleep apnea often perform worse on tasks requiring memory, attention, and mental flexibility (Fulda & Schulz, 2003). Sleep apnea is commonly diagnosed after an individual seeks treatment for snoring or fatigue, and the condition is usually detected through a sleep study. Narcolepsy Narcolepsy is a sleep disorder in which individuals experience extreme daytime sleepiness and sleep attacks. Narcoleptic episodes can last from a few seconds to several minutes and may occur during activities like standing, driving, or even walking (Nakamura et al., 2011). How Narcolepsy Differs: Unlike normal sleep patterns, which typically take an hour to enter REM sleep, narcoleptics often enter REM sleep almost immediately. Because REM sleep is associated with dreaming, narcoleptics often report vivid, dream-like images even when they haven’t fully fallen asleep. Causes of Narcolepsy: Narcolepsy is linked to a deficiency in orexin, a hormone that helps maintain wakefulness. Individuals with narcolepsy have fewer brain cells that produce orexin, making it difficult to stay awake (Nakamura et al., 2011). Narcoleptic episodes can be triggered by intense emotions, such as laughter. fMRI studies have shown that the emotional brain areas, including the amygdala and prefrontal cortex, become hyperactive during these episodes (Meletti et al., 2015). Treatment involves medications that help regulate sleep-wake cycles, allowing individuals with narcolepsy to function more normally (Mayer, 2012). 24 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 Overcoming Sleep Problems Many individuals experience sleep difficulties at some point, but there are many myths and misconceptions about what will help. For instance, some people use nightcaps or alcohol to induce sleep, but alcohol disrupts sleep quality, especially REM sleep, leading to grogginess the next day. Common Solutions for Sleep Problems: 1. Cannabis: Some people use cannabis to help with sleep, but studies have shown that cannabis can disrupt circadian rhythms and REM sleep. Long-term use may worsen sleep issues, leading most researchers to recommend finding other solutions for sleep disturbances (Lafaye et al., 2018). 2. Over-the-counter drugs: Sleep medications, such as sedatives, are widely available. However, they can be habit-forming, and users may develop a tolerance, requiring higher doses to achieve the same effect. Although modern sleep drugs are thought to be safer than older ones, few have been studied for long-term use (Krystal, 2009). Psychological Interventions: For most people, sleep problems can be overcome through psychological interventions, including practicing good sleep hygiene (Morin et al., 2006). Table 5.1 provides a list of nonpharmacological techniques for improving sleep: Table 5.1: Nonpharmacological Techniques for Improving Sleep: 1. Use your bed only for sleep (or sexual activity). 2. Don’t turn sleep into work; avoid trying too hard to fall asleep. 3. Keep your clock out of sight to avoid stressing about time. 4. Exercise early in the day to improve sleep quality. 5. Avoid substances that disrupt sleep (e.g., caffeine, alcohol, nicotine). 6. Write down worries before bed to reduce nighttime stress. 7. If unable to sleep, get out of bed for 30 minutes before trying again. 8. Wake up at the same time each day to set a daily rhythm. 9. Seek medical help if sleep problems persist beyond four weeks. Good sleep hygiene and consistent routines often solve sleep issues, making it unnecessary to rely on medications. By focusing on behavioral changes, most individuals can improve their sleep quality without altering their brain chemistry. 25 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 5.3 Drugs and Conscious Experience Coping with Drugs 1. Psychedelic Drugs for Coping: ○ Some doctors and psychologists suggest that psychedelic drugs like psilocybin (magic mushrooms) may help people cope with psychological issues such as anxiety, depression, and traumatic stress. ○ Despite being dismissed in the past due to the "war on drugs," recent research, such as that by Roland Griffiths at Johns Hopkins University, has shown promising therapeutic benefits. 2. Psilocybin: ○ Research has shown that psilocybin can: Improve emotional states, especially in patients with cancer (Griffiths et al. 2008, 2016). Help reduce symptoms of tobacco addiction (Johnson et al., 2014). Increase openness in personality (MacLean et al., 2011). "Micro doses" of psilocybin can improve cognitive flexibility and help alleviate symptoms of depression (Kuypers, 2020). ○ Despite these potential benefits, the use of psychedelics remains controversial in mainstream medicine. 3. Blurred Line between Medicine and Drug: ○ Many drugs, including psychedelics, blur the line between recreational use and medical therapy. The term "drug" and "medicine" are not always clearly distinguishable ○ Caffine and alcohol are both mainsteam parts of our culture – but are also drugs Effects on Consciousness Psilocybin: ○ Causes intense visual experiences, shifting a person’s moment-to-moment conscious experience to focus more on visual stimuli. Other Drugs (e.g., Ecstasy): ○ Can influence emotional responses, resulting in conscious experiences that are more emotional and less logical. Drugs can be useful tools for studying consciousness, as their effects directly alter sensory and cognitive processes. Short-Term Effects of Drugs 1. Neurotransmitters: ○ Drugs affect the brain by influencing neurotransmitters, which are chemical messengers. ○ These neurotransmitters are released by neurons into the synapse (the gap between neurons), where they either enhance or inhibit neuronal activity. ○ Drugs can act as agonists (enhance neurotransmitter activity) or antagonists (block neurotransmitter activity). 2. Mechanisms of Short-Term Effects: ○ The short-term effects of drugs can alter brain function through: Increasing the release of neurotransmitters into the synapse. Preventing reuptake (absorption) of neurotransmitters back into the neuron, extending their effect. 26 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 Blocking receptors that neurotransmitters would typically bind to. Mimicking neurotransmitters by binding to receptors and producing similar effects. 3. Example - Dopamine: ○ Many drugs, like ecstasy and opioid painkillers (OxyContin™), affect neurotransmitter systems. For instance, dopamine, linked to reward and pleasure, plays a significant role in the effects of drugs. ○ Dopamine release is linked to feelings of pleasure, reinforcing drug-taking behavior. 4. Brain Regions Involved: ○ Nucleus accumbens and ventral tegmental area (VTA) are key brain areas associated with the pleasurable effects of drugs. 5. Psychological Effects: ○ The relationship between drugs and neurotransmitters is complex and influenced by various psychological factors: The environment in which drugs are consumed plays a significant role. For example, overdoses are more likely in unfamiliar settings. Expectations and experiences with drugs also affect the intensity of drug effects. If a person expects a particular outcome (e.g., reduced anxiety from alcohol), the drug's effects may align with those beliefs. Additional Psychological Effects Psychological Preparations: If a person frequently uses a drug in a specific environment, their body may begin to prepare for the drug’s effects even before consumption. This means the same dose of a drug in a new environment may produce stronger effects, which explains why overdoses are more likely in unfamiliar settings. Learning Effects: As people take drugs over time, their brain and body start to associate the drug with specific bodily and brain effects, meaning the third or fourth time using the drug may lead to stronger or more noticeable effects. Expectation Influence: A person’s expectation of a drug’s effects (e.g., believing alcohol makes them less shy) can also change the drug’s impact. Long-Term Effects of Drugs 1. Tolerance: ○ Repeated use of drugs leads to tolerance, meaning higher doses are needed to achieve the same effect. ○ Tolerance develops because of down-regulated receptors, where the brain reduces the number of receptors or their sensitivity, which limits the impact of the drug over time (become more tolerant). ○ This is commonly seen with substances like opioids, which stimulate endorphin receptors, and over time, the body produces fewer endorphins naturally. 2. Addiction: ○ Drug addiction is a chronic brain disorder influenced by both psychological dependence (the emotional and cognitive drive to keep using - often driven be cravings and need to relieve negative emotions) and physical dependence (the body's adaptation to the drug - withdrawal symptoms – like anxiety, irratibility, seating, nausea, tremors – can emerge when the drug reduced or stopped, driving the need to consume more of it) ○ Addiction affects decision-making and self-regulation, often impairing a person's ability to stop using the substance despite knowing the harmful consequences. 27 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 3. Psychosocial Factors: ○ Psychological and social conditions that influence an individual’s likelihood of developing a drug addiction. For example, someone’s environment, like being in a high-stress situation or a social circle where drug use is common, increases the likelihood of dependency. Other examples: peer pressure, cultural background, etc. ○ Indigenous Perspectives on drug addiction highlight that social and historical contexts, like colonization, also affect addiction patterns. Treatment programs tailored to specific cultural and social contexts, such as Indigenous communities, have been suggested to be more effective. Commonly Abused Illegal Drugs (Table 5.3 Summary) This section categorizes drugs based on their psychological and chemical effects, tolerance, and the likelihood of dependence: 1. Stimulants: ○ Examples: Caffeine, cocaine, amphetamine, ecstasy. ○ Psychological Effects: Euphoria, increased energy, lowered inhibitions. ○ Chemical Effects: Increase dopamine, serotonin, norepinephrine activity. ○ Tolerance: Develops quickly. ○ Dependence Likelihood: High. 2. Hallucinogens: ○ Examples: LSD, psilocybin, DMT, ketamine. ○ Psychological Effects: Major distortion of sensory and perceptual experiences (fear, panic, paranoia). ○ Chemical Effects: Increase serotonin activity, block glutamate receptors. ○ Tolerance: Develops slowly. ○ Dependence Likelihood: Very low. 3. Opiates: ○ Examples: Heroin. ○ Psychological Effects: Intense euphoria, pain relief. ○ Chemical Effects: Stimulate endorphin receptors. ○ Tolerance: Develops quickly. ○ Dependence Likelihood: Very high. 4. Sedatives: ○ Examples: Barbiturates, benzodiazepines. ○ Psychological Effects: Drowsiness, relaxation, sleep. ○ Chemical Effects: Increase GABA activity. ○ Tolerance: Develops quickly. ○ Dependence Likelihood: High. 5. Alcohol: ○ Psychological Effects: Euphoria, relaxation, lowered inhibitions. ○ Chemical Effects: Primarily facilitates GABA activity, also stimulates endorphin and dopamine receptors. ○ Tolerance: Develops gradually. ○ Dependence Likelihood: Moderate to high. 6. Cannabis: ○ Psychological Effects: Euphoria, relaxation, distorted sensory experiences, paranoia. ○ Chemical Effects: Stimulates cannabinoid receptors. ○ Tolerance: Develops slowly. 28 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 ○ Dependence Likelihood: Low. Psychoactive Drugs Psychoactive drugs affect thinking, behavior, perception, and emotion. Many illegal drugs and prescription medications fall under this category. The boundary between legal and illegal drug use can sometimes be thin, as prescription drugs may be chemically similar to their illegal counterparts. Stimulants 1. Definition of Stimulants: ○ Stimulants are drugs that increase activity in the central nervous system (CNS), resulting in enhanced alertness, mood, and energy. Examples of stimulants include caffeine, nicotine, cocaine, amphetamines, and MDMA. 2. Mechanism of Action: ○ Stimulants increase levels of key neurotransmitters such as dopamine, serotonin, and norepinephrine in the brain. ○ Dopamine is closely linked to feelings of pleasure and reward. Stimulants typically block the reuptake of dopamine or directly stimulate its release, creating a feeling of euphoria. ○ Tolerance to stimulants can develop quickly, meaning users need increasing doses to experience the same effects. 3. Short-Term Effects: ○ Increased energy, alertness, and euphoria. ○ Elevated heart rate and blood pressure. ○ Reduced appetite and enhanced focus. ○ Negative effects may include anxiety, paranoia, restlessness, and jaw clenching (especially with MDMA). 4. Long-Term Effects: ○ Long-term use of stimulants can result in serious health complications, including cardiovascular problems (heart issues), cognitive deficits, and addiction. ○ Chronic users may experience anxiety, paranoia, and mental health issues. ○ Prolonged use of drugs like methamphetamine can lead to severe physical deterioration, including weight loss and dental problems. 5. MDMA (Ecstasy): ○ MDMA, or Ecstasy, is a stimulant that also has mild hallucinogenic effects. ○ It increases the release of serotonin, leading to feelings of emotional closeness, empathy, and enhanced sensory experiences. ○ Short-Term Effects: MDMA causes increased energy, feelings of connection with others, and heightened sensory perception. However, it also causes jaw clenching, sweating, and increased risk of dehydration and hyperthermia. ○ Long-Term Use: Chronic use can lead to serotonin depletion, resulting in depression, fatigue, and cognitive impairments. 6. Cocaine: ○ Mechanism: Cocaine blocks the reuptake of dopamine, serotonin, and norepinephrine, leading to intense euphoria. ○ Health Risks: Cocaine increases the risk of heart attack and stroke and can cause severe psychological issues, including paranoia and hallucinations. 29 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 7. Amphetamines: ○ Mechanism: Amphetamines stimulate the release of dopamine and norepinephrine and are often prescribed for conditions like ADHD. However, they are frequently abused recreationally. ○ Health Risks: Long-term use of amphetamines can result in psychosis, weight loss, and severe addiction. 8. Nicotine: ○ Nicotine is found in tobacco and increases dopamine levels, making it highly addictive. ○ Long-term nicotine use is associated with lung disease, cancer, and cardiovascular diseases. 9. Caffeine: ○ Caffeine is a legal stimulant found in coffee, tea, and energy drinks. It increases alertness by blocking adenosine receptors, which normally promote relaxation and sleep. ○ Health Effects: Excessive use can cause anxiety, jitteriness, insomnia, and increased heart rate. Hallucinogens 1. Definition of Hallucinogens: ○ Hallucinogens, also known as psychedelics, are substances that cause perceptual distortions. These distortions can affect visual (sight), auditory (sound), or tactile (touch) perception and may lead individuals to experience things differently than they normally would, causing users to feel detached from reality ○ Examples of hallucinogens include LSD, psilocybin, ketamine, DMT, and mescaline. 2. LSD (Lysergic Acid Diethylamide): ○ LSD is a synthetic hallucinogen that causes unusual sensory experiences by acting on the serotonin system, which plays a critical role in mood and perception. Influences how person perceives visual and auditory stimuli ○ Effects: LSD affects visual consciousness by triggering increased brain activity in visual processing areas, often leading to visual hallucinations. Users frequently report seeing bright colors or experiencing objects in a distorted manner. ○ Study: Research by Carhart-Harris et al. (2016) found that LSD leads to greater activity in visual areas and unusual connections between brain regions, contributing to a sense of "losing oneself" or finding new meaning in ordinary stimuli. ○ Long-Lasting Effects: LSD can last for more than 12 hours, with effects ranging from euphoria to panic and paranoia. 3. Psilocybin (Mushrooms): ○ Psilocybin is a naturally occurring hallucinogen found in certain mushrooms. It produces altered sensory and perceptual experiences similar to LSD. ○ Effects: Users of psilocybin experience visual and auditory distortions, heightened emotional sensitivity, and altered thought patterns. These effects last several hours. ○ Both LSD and psilocybin act on the serotonin system, which regulates mood and perception. 4. Short-Acting Hallucinogens: ○ Ketamine and DMT are shorter-acting hallucinogens often used recreationally. These substances can cause dissociative effects, where individuals feel detached from their body or environment. ○ Ketamine: Initially developed as a surgical anesthetic, ketamine induces dream-like states, memory loss, and dissociative experiences (a sense of being detached from one’s body or surroundings). It has become popular among university students and clubgoers. ○ DMT: Found naturally in certain plants, DMT is used both recreationally and in spiritual or religious ceremonies. It produces intense spiritual experiences where users often feel 30 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 connected to divine beings or communicate with non-human entities. Ayahuasca, a South American brew containing DMT, is used for spiritual rituals. 5. Salvia Divinorum: ○ Salvia Divinorum is an herb found in Central and South America, known for inducing intense but short-lived hallucinations. When smoked or chewed, salvia leads to dissociative experiences—a detachment between the self and surroundings. ○ Cultural Use: Salvia is used by shamans of the Mazatec people in Mexico for spiritual healing rituals. However, there is limited scientific evidence supporting its medicinal benefits. ○ Legal Status: As of February 2016, salvia is classified as a Schedule IV drug under the Controlled Drugs and Substances Act in Canada, making it illegal to sell, cultivate, or transport. 6. Negative Effects of Hallucinogens: ○ Flashbacks: Users of hallucinogens can experience flashbacks, where they re-experience the visual distortions or emotional changes from previous drug use long after the drug has left their system (long-term negative effect) ○ Memory problems and emotional instability, such as panic, paranoia, and anxiety, are also common long-term effects of hallucinogens. 7. Therapeutic Uses: ○ Research has explored the therapeutic potential of hallucinogens (like LSD and psilocybin) for treating conditions like anxiety in terminally ill patients and addiction (e.g., tobacco and alcohol dependence). Particularly important for mental health conditions that don’t respond well to conventional treatments ○ Clinical Trials: LSD and psilocybin have shown promise in reducing anxiety and helping individuals cope with terminal illness. Psilocybin and DMT are being studied for their ability to reduce addiction in patients when other treatments are ineffective. 8. Recreational vs. Medical Use: ○ The distinction between recreational drugs and medical drugs is often blurred, as substances like LSD and psilocybin are being explored for their mental health benefits. Opiates Definition: Opiates are drugs derived from the opium poppy, used primarily for pain relief. They include both natural (e.g., morphine) and synthetic (e.g., oxycodone) forms. Mechanism: Opiates bind to opioid receptors in the brain, mimicking endorphins (natural painkillers). This results in pain relief and euphoria. Examples: ○ Morphine: Used medically for severe pain relief. ○ Heroin: Illegal, highly addictive, and often abused recreationally. ○ Oxycodone: Prescription opioid often misused. Key Risks: ○ Tolerance: Users need higher doses over time to achieve the same effect. ○ Dependence and Addiction: Both physical and psychological dependence develop quickly, leading to severe withdrawal symptoms when use stops (e.g., pain, nausea, anxiety). ○ Overdose: High doses can cause respiratory depression, which can be fatal. 31 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 Sedatives Definition: Sedatives are drugs that slow down the central nervous system, used to induce calm, relieve anxiety, or promote sleep. Mechanism: Sedatives enhance the effects of GABA, an inhibitory neurotransmitter that reduces brain activity, leading to drowsiness and relaxation. Examples: ○ Benzodiazepines: (e.g., Xanax, Valium) prescribed for anxiety and insomnia. ○ Barbiturates: Once common, but now less frequently prescribed due to high overdose risk. Key Risks: ○ Addiction and Dependence: Long-term use can result in tolerance and dependence. ○ Withdrawal: Sudden withdrawal can lead to seizures, anxiety, and tremors. ○ Overdose: Can lead to coma or death, especially when combined with alcohol. Prescription Drug Abuse Definition: The misuse of prescribed medications, particularly painkillers, sedatives, and stimulants. Key Drugs: ○ Opioids: Prescribed for pain (e.g., oxycodone, fentanyl), often misused for their euphoric effects. ○ Benzodiazepines: Used for anxiety or sleep disorders but often misused for their calming effects. ○ Stimulants: Prescribed for ADHD (e.g., Adderall), but abused for energy boosts or cognitive enhancement. Causes of Abuse: Patients may misuse medications after developing tolerance or may use them recreationally. Consequences: ○ Addiction and Overdose: Especially common with opioids and benzodiazepines. ○ Increased Emergency Room Visits: Due to overdose or drug interactions. Alcohol Definition: Alcohol is a depressant that reduces brain activity, though in small amounts it initially acts as a stimulant by lowering inhibitions. Mechanism: Alcohol increases the activity of GABA (inhibitory neurotransmitter) and decreases glutamate (excitatory neurotransmitter), leading to reduced brain function. Effects: ○ Short-Term: Reduced inhibitions, impaired judgment, and coordination. ○ Long-Term: Chronic alcohol use can lead to liver damage (cirrhosis), brain damage, and addiction (alcoholism). ○ Withdrawal: Severe symptoms can include delirium tremens, seizures, and hallucinations, which can be life-threatening. Cannabis and the Teenage Brain Impact on Adolescence: Cannabis use during adolescence, a critical period of brain development, can negatively affect cognitive functions like memory and learning. Key Areas Affected: ○ Memory and Cognition: Regular cannabis use impairs memory retention and cognitive functioning, leading to poorer academic performance. 32 Chapter 4: 4.1, 4.2 and Chapter 5: 5.1, 5.3 ○ Emotional Regulation: Chronic use can affect emotional d