Sensation And Perception - Introduction To Psychology PDF

Introduction to psychology 2 Lecture Sensation and Perception Lecturer: Teona Gubianuri Sensation is the process by which we receive information from the environment What kind of information? A stimulus is a detectable input from the environment:...

Introduction to psychology 2 Lecture Sensation and Perception Lecturer: Teona Gubianuri Sensation is the process by which we receive information from the environment What kind of information? A stimulus is a detectable input from the environment: 1. Light—vision 2. Sound—hearing 3. Chemicals—taste and smell 4. Pressure, temperature, pain—sense of touch 5. Orientation, balance—kinesthetic senses Sensory processes are the initial steps to perception Transduction is the process of converting energy of a stimulus into neural activity. The stimulus is recoded as a neural pattern. Perception is the process of selecting and identifying information from the environment Perception is the interpretation of information from the environment so that we can identify its meaning Sensation usually involves sensing the existence of a stimulus, whereas perceptual systems involve the determination of what a stimulus is  Thresholds Absolute threshold  The point at which a stimulus can be detected 50 percent of the time  Difference threshold The minimal change in stimulation that can be reliably detected 50 percent of the time The Just Noticeable Difference (JND) The threshold for detecting that something has changed, such as the minimum change in volume necessary for us to tell that a sound is louder or softer Weber’s Law Suggests that the just noticeable difference is a percentage rather than an absolute amount  Signal Detection Theory Theory which suggests how individuals are able to detect a minimal stimulus (signal) among other background stimuli (noise). This may influence how individuals make a decision in a specific situation. Hit - In signal detection terms, correctly recognizing that a stimulus is present Miss - In signal detection terms, thinking that a stimulus is not there when it actually is present False Alarm - In signal detection terms, thinking that a stimulus is present when it actually isn’t present Correct Rejection - In signal detection terms, correctly recognizing that a stimulus isn’t present  Receptors Sensory adaptation: a decline in receptor activity when stimuli are unchanging (e.g., noticing a noisy fan as one first enters a room, yet the noise Specialized cells that are able seems to abate after a short time) to detect physical stimuli, such as light or sound  The process by which our senses adjust to different stimulus intensities Habituation or adaptation: a decline in response to a stimulus due to repeated presentation of the stimulus; this happens at the neural level.  Sensitivity With regard to signal detection, how easy it is to detect accurately  Criterion With regard to signal detection, how sure we want to be before we decide that a stimulus is present  Vision Vision begins with light entering the eye.  Human photoreceptors in the eye are sensitive to wavelengths of light energy called the visible spectrum  The visible spectrum ranges from red to violet Retina: layer containing two types of photoreceptors—rods and cones—that transduce light energy to electrochemical energy  Photoreceptors Cells that are sensitive to light Cones Rods Photoreceptors that provide Photoreceptors that our daytime vision and provide our ability to see color vision in dim light  Primarily reflects long wavelengths of light Color and Color Vision Primarily reflects short wavelengths Hue What is typically meant by the term color. Hue derives from some wavelengths of light being reflected more than others. White, black, and gray lack hue because they reflect all wavelengths approximately equally They lack hue because they reflect all wavelengths approximately equally (but white reflects more than black)  Hue What is typically meant by the term color. Saturation The hue relative to the amount of white. Adding white reduces the saturation Brightness The intensity of the light. Objects that reflect more light appear brighter The Trichromatic Theory Trichromatic Theory Suggests that we have three Some people lack one (or more) of the three types of types of color receptors that color receptors and so are unable to distinguish colors are sensitive to different parts that most people can differentiate. of the spectrum  Color deficiencies are much more common in males The instructions for the color receptors are on the X chromosome (male XY) The Opponent Process Theory Opponent Process Theory Suggests that color receptors are sensitive to opposing pairs of colors (e.g., stimulated by red and inhibited by green) How we perceive color is informed by types of color blindness  In monochromatic color blindness, the person cannot see any color at all.  In dichromatic color blindness, the person perceives only two of the three visual pigments  Ishihara color test  Our cones are actually most sensitive to a greenish yellow color  Audition “If a tree falls in the forest and no one is there to hear it, does it make a sound?” Begins with sound entering the ear  1. Sound is mechanical energy typically caused by vibrating objects.  2. Vibrations produce movement of air molecules (sound waves).  3. Moving one’s head helps in detecting the source of a sound Characteristics of sound  Frequency corresponds to the perceptual term pitch.  Frequency (number of waves per second) is measured in hertz (Hz).  Tall waves - Loud  Short waves - Quite  Amplitude corresponds to the perceptual term loudness (volume).  Amplitude is measured in decibels (dB).  The decibel scale is logarithmic, so a small change in dB is actually a large change in intensity.  Exposure to intense sounds can cause hearing loss Humans can only hear sounds from approximately 20 Hz to 20,000 Hz  THE GUSTATORY SENSE: TASTE Taste Buds Receptors that contain cells that are sensitive to taste Cross-adaptation The fact that some tastes or smells affect how other tastes or smells are perceived Nontasters Tasters Supertasters People who are insensitive to People who have an average sense People who have a particularly strong the taste of certain substances of taste for certain substances sense of taste for certain substances  THE OLFACTORY SENSE: SMELL Olfactory epithelium An area high in the nasal cavity where the olfactory sensory neurons, the neurons involved in the processing of smell, are located Odors or scents stimulate the olfactory epithelium  Odors can evoke highly emotional memories  On average, women detect odors more readily than men.  Also, brain responses to odors are stronger in women than in men (Kalat, 2007).  The Vestibular Sense Vestibular System Provides our sense of balance and knowledge of body position.  Feeling dizzy  A ringing or roaring in the ear  Pressure or pain in the affected ear  Hearing loss  Vertigo – feeling of spinning or that the world is spinning around THE SOMATOSENSORY SENSES Basic skin sensations include cold, warmth, pressure, and pain Touch plasticity When an area of the skin is used a lot, it becomes more sensitive Haptic Perception Perception based on touch and kinesthesis, such as when people read in Braille or find the right key in the dark by touch Pain “An unpleasant sensory and emotional experience associated with actual or potential damage, or described in terms of such damage.”- IASP Nociceptors Nerve endings that are sensitive to painful stimuli  Some are sensitive to pressure (e.g., smashing your thumb with a hammer)  Others to extreme heat or cold.  Thank you! CHAPTER 3 Sensation, perception (pp:85-86) Adaptation (pp:86-89) Different types of perception: Visual (pp:89-90) Auditory (pp:97-98) Somatosensory: Vestibular (pp: 103-104) Touch (pp:104-107) Pain (pp:108-109) Gustatory (p:109) Olfactory (p: 111) Perception (pp:113-116)