Sensation & Perception

What is sensation?

The detection of environmental stimuli by sensory receptors

What is perception?

The interpretation and organisation of sensory information by the brain

What is the difference between sensation and perception?

Sensation involves detecting stimuli, whereas perception involves interpreting meaning from stimuli

Which occurs first: sensation or perception?

Sensation

What is bottom-up processing?

Data-driven processing that begins with sensory input

What is top-down processing?

Knowledge-driven processing influenced by expectations, memory and experience

What is transduction?

The conversion of physical energy into neural signals

What is an absolute threshold?

The minimum intensity of a stimulus detected 50% of the time

What is a difference threshold (JND)?

The smallest detectable difference between two stimuli

What does JND stand for?

Just Noticeable Difference

What is Weber’s Law?

The stronger the original stimulus, the greater the change needed to notice a difference

What is sensory adaptation?

Reduced sensitivity to constant stimulation

Give an example of sensory adaptation

Not noticing the feeling of clothes on your skin after a few minutes

What are the four outcomes in signal detection theory?

Hit, miss, correct rejection and false alarm

What is a hit in signal detection theory?

Correctly detecting a stimulus that is present

What is a miss in signal detection theory?

Failing to detect a stimulus that is present

What is a false alarm in signal detection theory?

Incorrectly detecting a stimulus that is not present

What is a correct rejection in signal detection theory?

Correctly identifying that no stimulus is present

What property of light determines colour?

Wavelength

What property of light determines brightness?

Amplitude

What is the visible spectrum for humans?

Approximately 400–750 nanometres

What is the pathway light travels through the eye?

Cornea → pupil → lens → retina

What are rods?

Photoreceptors specialised for dim light and peripheral vision

What are cones?

Photoreceptors specialised for colour vision and detail

Which photoreceptors are mainly used for night vision?

Rods

Which photoreceptors are concentrated in the fovea?

Cones

What is the fovea?

The area of the retina responsible for the sharpest vision

What is trichromatic theory?

The theory that colour vision is based on three cone types: red, green and blue

What is opponent-process theory?

The theory that colour vision works through opposing colour pairs

Which colour pairs are involved in opponent-process theory?

Red-green, blue-yellow and black-white

What phenomenon does opponent-process theory explain?

Afterimages

Which theory explains colour vision at the retinal level?

Trichromatic theory

Which theory explains later colour processing in the brain?

Opponent-process theory

Why is perception considered constructive?

The brain actively organises and interprets sensory information

What influences top-down processing?

Expectations, schemas, prior knowledge and experience

What is an example of top-down processing?

Recognising a Dalmatian dog in a black-and-white image after identifying the pattern

What is an example of bottom-up processing?

Detecting lines, shapes and colours before recognising a face

What is the role of sensory receptors?

To detect environmental stimuli and begin transduction

What is the key difference between rods and cones?

Rods detect dim light and movement, whereas cones detect colour and fine detail

What type of processing is most influenced by memory and schemas?

Top-down processing

What is perceptual set?

A tendency to perceive stimuli in a particular way based on expectations

What is retinal disparity?

The difference between the images seen by each eye used for depth perception

What is convergence?

The inward turning of the eyes when focusing on nearby objects

What is linear perspective?

Parallel lines appearing to converge with distance

What is size constancy?

Perceiving objects as remaining the same size despite retinal image changes

What is shape constancy?

Perceiving objects as maintaining the same shape despite angle changes

What is colour constancy?

Perceiving objects as maintaining the same colour despite lighting changes

What is visual agnosia?

Inability to recognise objects despite intact vision

What are the Gestalt laws?

Principles explaining how the brain organises sensory information into meaningful wholes

What is the Gestalt law of proximity?

Objects close together are grouped together

What is the Gestalt law of similarity?

Similar objects are grouped together

What is the Gestalt law of closure?

Incomplete figures are perceived as complete

What is the Gestalt law of common fate?

Objects moving together are grouped together

What is the Gestalt law of good continuation?

The brain prefers smooth continuous patterns

What is the Gestalt law of familiarity?

Objects are grouped into familiar patterns

A person can describe a rose but cannot identify it until smelling it. Which disorder explains this?

Visual agnosia

Reading the word “RED” printed in blue ink interferes with naming the ink colour. What effect is this?

Stroop effect

A person recognises a Dalmatian dog only after identifying the black-and-white pattern. What type of processing is this?

Top-down processing

A person first detects lines and shapes before recognising a face. What type of processing is this?

Bottom-up processing

A person stops noticing the feeling of their watch after wearing it for a few minutes. What concept explains this?

Sensory adaptation

A person hears their phone vibrate when it actually did not. Which signal detection outcome is this?

False alarm

A person correctly notices their name being called in a noisy room. Which signal detection outcome is this?

Hit

A person perceives incomplete shapes as whole figures. Which Gestalt principle explains this?

Closure

A driver perceives railway tracks as moving closer together in the distance. Which monocular depth cue explains this?

Linear perspective

A nearby object produces greater difference between the two retinal images. Which binocular cue explains this?

Retinal disparity

A person still perceives a door as rectangular even when it is partly open. What perceptual constancy is this?

Shape constancy

What is perceptual organisation?

The process of organising sensory information into meaningful patterns

Why are Gestalt laws important?

They help the brain organise complex sensory information efficiently

What is monocular depth perception?

Depth perception using one eye

What is binocular depth perception?

Depth perception using both eyes

What is texture gradient?

A monocular cue where distant objects appear smoother and less detailed

What is relative size?

A monocular cue where smaller retinal images are perceived as farther away

What is motion parallax?

A monocular cue where nearby objects appear to move faster than distant objects

What is perceptual ambiguity?

A stimulus that can be interpreted in multiple ways

What are perceptual illusions?

Misinterpretations of sensory information

Why are perceptual illusions important in psychology?

They demonstrate that perception is constructive

A nearby object appears to move faster than distant scenery while driving. Which depth cue explains this?

Motion parallax

Objects farther away appear smoother and less detailed. Which depth cue explains this?

Texture gradient

A person interprets the same image in two different ways. What concept explains this?

Perceptual ambiguity

What are feature detectors?

Specialised neurons that respond to specific visual features such as edges, angles or movement

Who discovered feature detectors?

Hubel and Wiesel

Why are feature detectors important?

They help the brain process complex visual information

What is perceptual narrowing?

Increased sensitivity to familiar stimuli and reduced sensitivity to unfamiliar stimuli over time

What is parallel processing?

The brain processing multiple aspects of sensory information simultaneously

What aspects of vision are processed in parallel?

Colour, motion, form and depth

A neuron responds specifically to horizontal lines. What type of neuron is this?

Feature detector

An infant becomes better at recognising faces from their own culture than unfamiliar cultures. What concept explains this?

Perceptual narrowing