Chapter 5: Sensation & Perception

Question 1

Define colour constancy

Answer 1

Colour constancy is the ability to perceive colors of objects, invariant to the color of the light source.

Question 2

Define stimulus, sensation, transduction, and perception

Answer 2

Stimulus is any event or object that elicits a sensory response. Sensation is the process of detecting physical energy from the environment. Transduction is the conversion of this energy into neural signals. Perception is the interpretation of these signals by the brain.

Question 3

Distinguish between bottom-up and top-down processing

Answer 3

Bottom-up processing is data-driven and starts with sensory input, while top-down processing is concept-driven and relies on prior knowledge and expectations.

Question 4

Define psychophysics

Answer 4

Psychophysics is the study of the relationship between physical stimuli and the sensations and perceptions they produce.

Question 5

Explain what the absolute threshold of awareness is

Answer 5

The absolute threshold of awareness is the minimum intensity of a stimulus that can be detected 50% of the time.

Question 6

What is the relationship between the absolute threshold and sensitivity?

Answer 6

The absolute threshold is inversely related to sensitivity; lower thresholds indicate higher sensitivity.

Question 7

Explain signal detection theory, and be prepared to apply it to examples

Answer 7

Signal detection theory explains how we detect signals amidst noise, considering both sensitivity and decision criteria.

Question 8

Distinguish between liberal and conservative bias

Answer 8

Liberal bias refers to a tendency to say ‘yes’ to signals, while conservative bias refers to a tendency to say ‘no’ unless certain.

Question 9

Define just-noticeable difference

Answer 9

Just-noticeable difference (JND) is the smallest difference in stimulus intensity that a specific sense can detect.

Question 10

Define Weber’s law/Weber’s fraction

Answer 10

Weber’s law states that the JND is a constant proportion of the original stimulus intensity.

The basic principle is that larger stimuli require larger differences to be noticed.

Question 11

Explain what adaptation is, and identify the benefits of sensory and perceptual adaptation

Answer 11

Adaptation is the process by which sensitivity to a stimulus decreases over time. Benefits include increased efficiency in processing important changes in the environment.

Question 12

Describe the properties of light

Answer 12

Light has properties of wavelength (color), intensity (brightness), and purity (saturation).

Question 13

Identify and explain the functions of the eye’s major structures

Answer 13

The major structures include the cornea (focuses light), lens (adjusts focus), retina (detects light), and optic nerve (transmits signals to the brain).

Question 14

Explain the difference between the two kinds of photoreceptor cells: cones and rods

Answer 14

Cones are responsible for color vision and function best in bright light, while rods are more sensitive to light and are responsible for vision in low light.

Question 15

Explain (in broad terms) the process of visual transduction

Answer 15

Visual transduction is the conversion of light into electrical signals by photoreceptors in the retina.

Question 16

Explain the process by which light/dark adaptation works

Answer 16

Light adaptation occurs when moving from dark to bright environments, adjusting sensitivity quickly, while dark adaptation occurs when moving from bright to dark, adjusting more slowly.

Question 17

Explain what rhodopsin is

Answer 17

Rhodopsin is a light-sensitive pigment found in rods that plays a key role in vision under low light conditions.

Question 18

Describe the property of cones that allows colour vision

Answer 18

Cones contain photopigments that are sensitive to different wavelengths of light, enabling color perception.

Question 19

Explain what the trichromatic theory of colour vision is

Answer 19

The trichromatic theory posits that color vision is based on the activity of three types of cones sensitive to red, green, and blue light.

Question 20

Explain what the opponent-process theory of colour vision is

Answer 20

The opponent-process theory suggests that color perception is controlled by opposing pairs of colors: red-green, blue-yellow, and black-white.

Question 21

Explain why the visual system is described as ‘hierarchical’

Answer 21

The visual system is hierarchical because visual information is processed in stages, from simple features to complex representations.

Question 22

Explain how visual information travels from the eyes to the brain

Answer 22

Visual information travels from the retina through the optic nerve to the thalamus and then to the visual cortex in the brain.

Question 23

Define feature detectors

Answer 23

Feature detectors are specialized neurons in the visual cortex that respond to specific features of visual stimuli, such as edges or movement.

Question 24

Define visual association cortex

Answer 24

The visual association cortex integrates and interprets visual information, allowing for recognition and understanding of visual stimuli.

Question 25

Define visual agnosia and prosopagnosia

Answer 25

Visual agnosia is the inability to recognize objects despite intact vision, while prosopagnosia is the inability to recognize faces.

Question 26

Identify the ‘what’ and ‘where’ pathways of visual processing (i.e., the ventral and dorsal pathways)

Answer 26

‘What’ pathway (ventral) is involved in object recognition, while ‘where’ pathway (dorsal) is involved in spatial awareness and movement.

Damage to these areas can lead to deficits in recognizing objects or navigating space.

Question 27

What is Gestalt psychology?

Answer 27

Gestalt psychology is a theory that emphasizes the human ability to perceive patterns and wholes in visual stimuli.

Question 28

What are the Gestalt principles for organizing visual data and recognizing objects?

Answer 28

Gestalt principles include figure-ground, similarity, proximity, continuity, and closure, which explain how we group visual elements.

Question 29

What do reversible figures demonstrate?

Answer 29

Reversible figures demonstrate how perception can shift between different interpretations of the same visual stimulus.

Question 30

What are illusory contours, and how are they an example of top-down processing?

Answer 30

Illusory contours are perceived edges that are not actually present, illustrating how our brain fills in gaps based on context and expectations.

Question 31

Explain how both binocular and monocular cues are used for depth perception

Answer 31

Binocular cues involve both eyes (e.g., retinal disparity), while monocular cues involve one eye (e.g., relative size, texture gradient) to perceive depth.

Question 32

Explain how the brain maintains perceptual stability despite sensory variability

Answer 32

The brain maintains perceptual stability through mechanisms like size constancy and color constancy, allowing us to perceive objects as stable despite changes in sensory input.

Question 33

Describe (in broad terms) the functions of the components of the ear

Answer 33

The outer ear collects sound waves, the middle ear amplifies them, and the inner ear converts them into neural signals.

Question 34

Identify the two different ways we perceive pitch

Answer 34

Pitch is perceived through the place theory (location of stimulation on the cochlea) and frequency theory (rate of neural firing).

Question 35

Explain how our two ears help us localize sound

Answer 35

Our two ears help localize sound through interaural time differences and interaural level differences, allowing us to determine the direction of sounds.

Question 36

Identify the receptors that give rise to tactile sensations

Answer 36

The receptors for tactile sensations include mechanoreceptors, thermoreceptors, and nociceptors.

Question 37

What property of these receptors allow us to make fine-grained discriminations when touching objects or being touched?

Answer 37

The density and distribution of mechanoreceptors in the skin allow for fine-grained tactile discrimination.

Question 38

Explain where and how touch sensations received throughout the body are organized in the brain

Answer 38

Touch sensations are organized in the somatosensory cortex, where different body parts are represented in a topographical manner.

Question 39

Define tactile agnosia and identify brain regions that may be damaged in an individual with this condition

Answer 39

Tactile agnosia is the inability to recognize objects by touch, often due to damage in the parietal lobe.

Question 40

Explain what is special about skin receptors specialized for social touch

Answer 40

Skin receptors specialized for social touch are sensitive to gentle touch and play a role in social bonding and emotional communication.

Question 41

Define interoception; explain the role the insula plays in this process and the links between interception and emotion

Answer 41

Interoception is the sense of the internal state of the body, with the insula integrating this information and linking it to emotional experiences.

Question 42

Define proprioception

Answer 42

Proprioception is the sense of body position and movement, allowing us to coordinate actions and maintain balance.

Question 43

Describe how the vestibular system works; explain how the vestibular and visual systems work together and how conflict between the vestibular and visual systems can create motion sickness

Answer 43

The vestibular system detects head movement and position. It works with the visual system to maintain balance, and conflict between the two can lead to motion sickness.

Question 44

Explain why olfaction is important

Answer 44

Olfaction is important for detecting environmental hazards, finding food, and social communication.

Question 45

Describe the transduction of olfactory stimuli

Answer 45

Olfactory transduction occurs when odor molecules bind to receptors in the nasal cavity, triggering neural signals to the brain.

Question 46

Explain why smells are often linked to emotions and memories

Answer 46

Smells are linked to emotions and memories because the olfactory bulb is closely connected to the limbic system, which processes emotions and memory.

Question 47

Explain why smell contributes to perception of flavour

Answer 47

Smell contributes to flavor perception by providing additional sensory information that enhances taste.

Question 48

Summarize individual differences in olfaction

Answer 48

Individual differences in olfaction can be influenced by genetics, age, and health, affecting sensitivity and preferences.

Question 49

Identify the evolutionary purpose of our sense of taste

Answer 49

The sense of taste evolved to help organisms identify nutritious food and avoid harmful substances.

Question 50

Explain how transduction of gustatory stimuli works

Answer 50

Gustatory transduction occurs when taste molecules bind to receptors on taste buds, generating neural signals.

Question 51

Describe where taste information is processed in the brain

Answer 51

Taste information is processed in the gustatory cortex, located in the insula and frontal lobe.

Question 52

Explain what the McGurk effect is and why it happens

Answer 52

The McGurk effect is a perceptual phenomenon where conflicting auditory and visual information leads to a different perception of speech.

This illustrates visual dominance in speech perception.

Question 53

Describe the rubber hand illusion

Answer 53

The rubber hand illusion is a phenomenon where a person feels a fake hand as their own when it is stroked in sync with their real hand.

Question 54

Explain how sensory systems interact to create full perceptions of the world (sensory integration)

Answer 54

Sensory integration is the process by which the brain combines information from different sensory modalities to create a coherent perception.

Question 55

Explain how our pre-existing knowledge, expectations, and motivations shape perception

Answer 55

Pre-existing knowledge, expectations, and motivations influence perception by guiding attention and interpretation of sensory information.