PSY - Chapter 4: Sensation, Perception & Psychophysics

What is sensation?

Detecting physical stimuli through sensory receptors.

What is perception?

Interpreting and giving meaning to sensory information.

What are the three steps of sensation?

1. Receive → sensory receptors detect stimulus.

2. Transduce → convert stimulus into neural signals.

3. Deliver → send information to the brain.

What is sensory adaptation?

A decrease in sensitivity to a constant, unchanging stimulus.

Example: You stop noticing the smell of your perfume after wearing it for a while.

What is psychophysics?

The scientific study of the relationship between physical stimuli and psychological experiences.

What is a threshold?

The level at which a stimulus can be detected.

What is the absolute threshold?

The minimum intensity of a stimulus that can be detected 50% of the time.

What is the difference threshold/JND?

The smallest difference between two stimuli that can be detected.

What is Weber's Law?

The JND depends on the proportion/percentage of the original stimulus, not simply the amount of change.

Example: Adding 1 lb to a 10-lb object may be noticeable, but adding 1 lb to a 100-lb object may not be.

What is signal detection theory?

It explains how we decide whether a stimulus/signal is present, especially when there is uncertainty or noise.

Signal there + YES = HIT

Signal there + NO = MISS

Signal absent + NO = CORRECT REJECTION

Signal absent + YES = FALSE ALARM

What do the cornea, pupil, and lens do?

The cornea protects/focuses light, the pupil lets light in, and the lens focuses light onto the retina.

What is accommodation?

The lens changes shape to focus on objects at different distances.

What is the difference between rods and cones?

Rods work in dim light and detect contrast; cones detect color and detail in bright light.

What are visual acuity, sensitivity, and the blind spot?

Acuity = seeing fine details; sensitivity = detecting dim light; blind spot = where the optic nerve leaves the retina and there are no receptors.

What is the visual pathway?

Rods/Cones → Bipolar cells → Ganglion cells → Optic nerve → Brain.

What do wavelength and amplitude determine?

Wavelength determines color (hue); amplitude determines intensity/brightness.

What are the two major color theories?

Trichromatic theory says we have 3 types of cones; opponent-process theory says color is processed in opposing pairs: red-green, blue-yellow, black-white.

What does Gestalt psychology focus on, and who helped found it?

Perceiving the whole rather than individual parts; Max Wertheimer was one of its founders.

What are similarity, proximity, closure, and figure-ground?

Similarity = group things that look alike; proximity = group things close together; closure = fill in gaps; figure-ground = separate an object from its background.

What are retinal disparity and convergence?

Retinal disparity = each eye sees a slightly different image; convergence = eyes turn inward when viewing something close.

What are relative size and linear perspective?

Smaller-looking objects seem farther away; parallel lines appear to meet in the distance.

What are pitch, loudness, and timbre?

Pitch = high/low, based on frequency; loudness = loud/quiet, related to amplitude; timbre = quality that makes sounds different.

What are the three theories of pitch?

Frequency = pitch follows frequency; volley = groups of neurons fire together; place = different frequencies activate different cochlear locations.

What are the vestibular and cutaneous senses?

Vestibular = balance/head position; cutaneous = touch, warmth, cold, pressure, and pain.

What is gate control theory of pain?

A neural “gate” in the spinal cord can allow pain signals through or block them.

What are olfaction and taste, and what are the five basic tastes?

Olfaction = smell; taste detects chemicals on the tongue. The five tastes are sweet, salty, sour, bitter, and umami.

What are kinesthesia and synesthesia?

Kinesthesia = sense of body position/movement; synesthesia = stimulation of one sense automatically triggers an experience in another.