Sensation and Perception in Psychology

• These notes cover key concepts in psychology, including sensation, perception, consciousness, learning, and related biological processes.

Sensation

• Detection of physical energy by sense receptors at a physiological level.
• Raw sensory data processed by receptors in eyes, ears, nose, skin, and tongue.

Perception

• The brain's interpretation of raw sensory data, a psychological component.
• Sensations are processed in the brain to interpret information.

Perceptual Illusions

• Perception of a stimulus that does not match its physical reality.
• Ebbinghaus-Titchener illusion demonstrates how context affects size perception.

Context Role

• Bigger blue dots make the orange dot appear smaller and vice versa.
• Surrounding context influences the perception of visual stimuli.

Blind Spots

• The optic disc lacks photoreceptors where the optic nerve exits the eye.
• The brain fills in missing information based on the surrounding context.

Transduction

• The nervous system converts an external stimulus into electrical activity within neurons.
• Sense receptors are specialized cells performing transduction.

Doctrine of Specific Nerve Energies (Johannes Muller)

• Sensations are determined by the nature of the sense receptor, not the stimulus.
• Rubbing eyes causes you to see light due to pressure on eye receptors.

Phosphenes

• Sensations of light are caused by pressure on eye's receptor cells.

Sensory Adaptation

• Activation is highest when a stimulus is first detected, diminishing over time.
• Important, stable information is less important than changing information.

Psychophysics

• Study of how we perceive sensory stimuli based on physical characteristics.
• Absolute Threshold: The lowest level of a stimulus needed for detection 50% of the time.
• Just Noticeable Difference: Smallest detectable change in stimulus intensity.
• Weber's Law: The JND has a constant proportional relationship with the original stimulus intensity.

Cross-Talk Between Senses

• Cross-modal processing influences perception, relying on multiple senses.
• McGurk Effect: Integrates visual and auditory information.

Synesthesia

• A condition where people experience cross-modal sensations, generally hereditary.
• Grapheme-colour synesthesia: Visual cortex becomes active, seeing symbols as different colours.
• Lexical-taste synesthesia: Words have associated tastes.

Selective Attention

• Process of selecting one sensory channel while minimizing others.
• Reticular activating system: Filters information in the brainstem for relevance.
• Broadbent's Filter Theory of Attention: Irrelevant information is filtered out during focus.
• Dichotic Listening Task: Participants listen to different audio in each ear, asked to ignore one.
• People are typically poor at answering questions about the ignored audio.

Shadowing

• Anne Treisman's research suggests attentional filtering is more nuanced.
• Information from the ignored ear can sometimes slip through, especially if meaningful.
• Cocktail Party Effect: Awareness of relevant stimuli outside of attention.

Inattentional Blindness

• Failure to notice visible stimuli when attention is focused elsewhere.

Change Blindness

• Failure to detect changes in the environment.

Light Spectrum

• Humans respond to a narrow spectrum of light (400-700 nm).
• Brightness: The amount of light reflected back to the eye.
• Hue: Colour of light, with each light having a specific wavelength.

Major Parts of the Eye

• Iris: Controls how much light enters the eye by controlling pupil size.
• Pupil: Hole where light enters the eye.
• Pupillary reflex: Pupil automatically restricts in bright light.
• Pupil dilation: Pupil dilation relates to cognitive processes and arousal.
• Cornea: Transparent cells focusing light on the back of the eye.
• Lens: Focuses images and changes curvature to reflect light onto the retina.
• Retina: Membrane at the back of the eye.
• Cones: High light requirement, colour vision, located in the fovea.
• Rods: Low-light vision, dark adaptation, absent in fovea.
• Accommodation: The lens corrects focus for near or far objects.

Fovea

• Divot in the retina with cones, processing high detail and colour information.
• Cone types: There are 3 cone types: red, green and blue.

Hubel and Wiesel Experiment

• Feature detectors in the occipital lobe respond best to specific stimuli.

Trichromatic Theory

• Colour vision is based on sensitivity to three primary colours: blue, green, red.

Opponent Process Theory

• One colour suppresses another.
• Explains afterimages.

Sound

• Sound is vibration.
• Pitch: Wave frequency (Hz), perceiving 20-20000 Hz.
• Loudness: Amplitude of sound waves (dB).

Major Parts of the Ear

• Outer ear: Includes the pinna, ear canal, and ear drum.
• Middle ear: Ossicles (hammer, anvil, stirrup) vibrate and transmit sound.
• Inner ear: Cochlea converts vibration into neural activity.
• Organ of Corti and basilar membrane: Located inside the cochlea and contain hair cells.

Transduction in Senses

• Actions potentials are generated in each system.
• Occurs at hair cells, rods and cones, olfactory neurons and taste buds.

Properties of Smell vs Taste

• Olfaction (smell) and gustation (taste) work together.
• Odours are airborne chemicals, can distinguish 2000-4000 different odours.
• We are sensitive to five basic tastes: sweet, salty, sour, bitter, and umami.

Somatosensory System

• Responds to stimuli applied to the skin and processes multiple types of information.
• Action potential rate relates to stimulus intensity and touch information processing.
• Mechanoreceptors are specialized nerve endings in the skin.

Bottom-up Processing

• Relies on sensory data alone.
• The whole stimulus is constructed from parts to form meaningful concepts.

Top-down Processing

• Raw stimulus modified by experiences and knowledge.
• Context influences object interpretation.

Gestalt Principles of Object Perception

• Rules govern how we perceive objects as wholes.
• Proximity: Objects close together are perceived as groups.
• Similarity: Similar objects are seen as a whole
• Continuity: Objects are perceived as unbroken.
• Closure: Brains fill in missing information.
• Symmetry: Objects arranged symmetrically are perceived as wholes.

Figure-ground

• Focus on the central figure and ignore the background.

Motion

• The brain compares visual frames.

Phi Phenomenon

• Successive flashing lights perceived as movement.

Depth Perception

• Ability to see spatial relations in three dimensions.
• Monocular cues: Rely on one eye (relative size, texture gradient, interposition).
• Linear perspective: Parallel lines converge in the distance.
• Height in plane: Distant objects appear higher.
• Light and shadow: Give 3-D form.
• Motion parallax: Nearby objects appear to move faster.
• Binocular cues: Require both eyes (disparity, convergence).
• Visual cliff experiment: Babies show hesitation at a perceived cliff, demonstrating innate depth perception.

Consciousness

• Awareness of internal and external stimuli.
• Subjective and dynamic.

Mindfulness Meditation

• Directing awareness to breath, thoughts, sensations.
• Mindfulness meditation can improve both mental and physical health by observing without judgement.

Mind Wandering

• Task-unrelated thoughts, intentional or unintentional.
• Benefits: Future planning, creative thoughts, distraction, relieve boredom.
• Default Mode Network: Active when at rest, task negative, and mind wandering.
• Dorsal Attention Network: Active during tasks, task positive, and engaged attention.

Biology of Sleep

• We spend about 1/3 of our lives asleep.
• Provides benefits for learning and long-term memory.
• Okano correlational study: Positive correlation between hours slept and test scores.
• Gais and coworkers: Sleep helps memory consolidation.
• Wilhelm and coworkers: Sleep improves task performance expectations

Why do we Need Sleep?

• Promotes insight, problem solving, and immune system function.
• Conserves energy and aids neural development and learning.

Circadian Rhythm

• Cyclical biological changes occur on a 24-hour basis.
• Regulated by the suprachiasmatic nucleus (SCN) in the hypothalamus.

Sleep Needs

• Newborns need 16 hours.
• University students need 7-9 hours.
• Some have a genetic DEC2 mutation and can function on <6 hours.

Five Stages of Sleep

• Cycle through stages in roughly 90-minute cycles.
• Stages 1-4 are NREM sleep, stage 5 is REM sleep.
• Stage 1: Light sleep, brain waves slow.
• Stage 2: has sleep spindles and K-complexes.
• Stage 3 and 4: deep sleep, delta brain waves.
• Stage 5: REM sleep, brain activity similar to wakefulness.

Brain Waves

• Beta: Normal waking.
• Alpha: Awake but deeply relaxed.
• Theta: Light sleep.
• Delta: Deep sleep.
• REM: REM sleep (mimics beta).

Sleep Disorders

• Insomnia is the most common disorder.
• Narcolepsy: Rapid onset of sleep.
• Sleepwalking: Occurs during deep sleep stage 3 and 4.

Dreams

• Universal experience.
• Dreaming helps with storing, reviewing, and updating memories, and simulating events.
• NREM Dreams: Shorter, thought-like, concerned with daily tasks.
• REM Dreams: Emotional, illogical, perceptually vivid.
• Lucid Dreaming: Knowing that a dream is a dream.
• Freud's dream protection theory: Dreams represent unconscious desires.
• Activation synthesis theory: Brainstem activity generates dreams, reflecting a meaningful story.
• Neurocognitive theory: Dreams reflect cognitive abilities and experiences.

Hallucinations

• Realistic perceptual experiences in the absence of external stimuli.

Hypnosis

• Imaginative suggestions to elicit changes in consciousness.
• Begins with induction.

Hypnosis Myths

• Not a trance state, not sleep-like, people are aware, does not enhance memory accuracy.

Vegetative State

• A person is awake, however shows no signs of awareness.

Psychoactive drugs

• Substances alter consciousness.
• Depressants: Depress the CNS.
• Stimulants: Rev up heart rate, respiration, and blood pressure.
• Opiates: Induce euphoria, relieve pain, and induce sleep.
• Psychedelics: Produce dramatic alterations in perception, mood, and thought.

Learning

• A change in behaviour or thought as a result of experience.
• Habituation: Decrease in response to a stimulus over time.
• Sensitization: Increase in responding over time.
• Conditioning: Learning connections between events.

Classical Conditioning

• Pavlov's dogs demonstrate it.
• Neutral stimulus turns into a conditioned stimulus through pairing.

Principles of Classical Conditioning

• Acquisition: Learning phase.
• Extinction: Reduction of the conditioned response.
• Spontaneous Recovery: Return of conditioned response after time.
• Renewal Effect: Return of conditioned response.
• Stimulus Generalization: Similar stimuli elicit the same response.
• Stimulus Discrimination: Ability to distinguish between stimuli.
• Higher-Order Conditioning: A second conditioned stimulus evokes the conditioned response.

Operant Conditioning

• Learning controlled by consequences.
• Reinforcers: Increase the probability of a response.
• Positive reinforcement: Presenting a positive stimulus.
• Negative reinforcement: Removing a negative stimulus.

Punishment

• Decreases the probability of a response.
• Positive punishment: Presenting a stimulus.
• Negative punishment: Removing a positive stimulus.
• Continuous Reinforcement: Response is rewarded every time.
• Partial Reinforcement: Reinforce responses some of the time.

Schedules of Reinforcement

• Fixed Ratio: Reinforced after a specific number of response.
• Variable Ratio: Rewards vary.
• Fixed Interval: Reinforcement after a fixed amount of time.
• Variable Interval: Reinforcement delivered at varying intervals.

Shaping

• Conditioning a target behaviour by progressively reinforcing closer behaviours.
• Chaining: Method for teaching a series of behaviours.
• Latent Learning: Learning that is not directly observable.

Observational Learning

• Learning by watching others.
• Mirror Neurons: Activated when observing action.
• Conditioned Taste Aversion: Learned avoidance of a particular taste.
• Preparedness: Evolutionary predisposition to fear certain things.