Topic 4 Flashcards
Prosopagnosia
Sensing & perceiving are connected but different
Cognitive disorder of face
perception
Difficulty perceiving/recognizing faces
Face blindness
Intact vision
Sensation
Detection of physical energy by the sense organs
Perception
The brain’s interpretation of raw sensory data
Sensory receptors
Specialized neurons that respond to different types of stimuli
Our sensory systems provide information about our surroundings, allowing us to navigate and interact with our environment.
Photoreception: light
Mechanoreception: pressure, vibration, movement
Chemoreception: chemical
Transduction
Conversion of one energy form into another
Receive sensory information via sensory receptor cells
Transform the stimulation into neural impulses (action potentials)
Deliver the neural information to the brain
The multitasking brain
Bottom-up:
* Perception based on building simple input into more complex perceptions\
Top-down:
* A perceptual process in which memory and other cognitive processes are required for interpreting incoming sensory information
Sensory adaptation
Activision is highest at first detection, then sensory adaptation occurs
Sensory receptor cells become less responsive to a stimulus that is unchanging, becomes less noticeable
Adaptive - conserve energy, focus on novelty & changes
Psychophysics
The measurement of sensation
Sensation begins with a detectable stimulus
Absolute threshold:
* Minimum intensity of a stimulus that a person can detect half the time
Subliminal perception
Perception of stimuli that are presented at below absolute threshold
Perception != persuasion, little practical application
Just noticeable difference (JND)/Difference threshold
The degree of difference that must exist between two stimuli before the difference is detected:
* Many decisions rely on our ability to detect small differences
Weber’s law:
* JND between 2 stimuli is not an absolute amount, but an amount relative to the intensity of the first stimulus
* The more intense the initial stimulus the larger the difference needs to be
JND & Marketing
JND applies to what we buy
Marketers are concerned that:
* Positive changes are discernible (at or just above JND)
* Negative changes are not discernible (below JND)
* Changes subtle enough to keep current customers
The role of attention in S&P
Flexible attention is critical
Selective attention:
* Focusing on a specific aspect of sensory input while ignoring other stimuli in the environment
* Attention as a bottleneck
* The other channels are still being processed at some level
We are poor at detecting stimuli in plain sight if our attention is focused elsewhere
Inattentional blindness
* Failure to detect an unexpected stimulus in plain sight
* Limited attentional resources, focus on what we deem important
Change blindness
* Failure to detect changes in your environment
* Limited resources further constrained by age, distraction
Vision
Stars with light, the physical energy that stimulates the eye
- Transduction: photoreceptors (rods & cones)
The eye
The eye
* Muscle ring that controls pupil size
* Controls the amount of light entering the eye
Cornea
* Light enters through the cornea, passes through the pupil, and hits the lens
* The lens focuses light rays into an image on the retina of the eyeball
Retina
* The light-sensitive back inner surface of the eye - nerve cells here
* Contains rods & cons
Optic nerve
* Carries neural impulses from eye to brain
* Blind spot: the point where the optic never leaves the eye no receptor cells
The eye: visions window
Iris’s main job is controlling the light that enters but also:
* The eye adjusts to imaginary light
* Iris constricts with disgust or when you are about to say “NO”
* Dilates with romance or trust (autonomic arousal)
Rods & cones
Retainal receptors
Rods:
* 100 - 125 mil
* Detect black, white, and gray and are sensitive to movement
* Peripheral & twilight vision
* Low light situations
* Located in peripheral
Cons
* 5 - 6 mil
* Shap focus colour perception, detail
Vision: how we percicve shape and contour
Feature detectors:
* Cells in the visual cortex that respond are sensitive to specific features of Env’t
Some cells respond to lines in specific orientations:
* Simple cells - lines, angles
Some cells respond to particular shapes
Color vision
Different theories of color perception
Trichromatic theory
* The retina contains red, green & blue receptors - when stimulated, these receptors can produce the perception of any color
* Consists of three types of corners in the eye
Opponent process theory:
* We perceive colors in terms of three pairs of opponent colors: red or green, blue or yellow, and black or white
Color processing combines the trichromatic theory and the opponent processing theory
Two stages
* The retina’s red, green, and blue cones respond in varying degrees to different color stimuli
* The cone’s responses are processed by opponent-process cells
When we can’t see
Blindness can result in the reorganizing of other sensory cortices and changes in other senses
Echolocation might improve following blindness
Visual agnosia:
* Object recognition deficit
* Damage to higher visual cortical areas
Blindsight:
* Above chance visual performance and cortically blind individuals with damage to area V1
Perceptual organization
How do we organize and integrate sights so they become meaningful perceptions
Perception is a constructive process We go beyond the stimuli that are presented to construct a meaningful situation
We don’t passively respond to visual stimuli that fall on the retina, we actively try to organize and make sense of what we see
Gestalt principle
Principles that determine how we organize information into meaningful wholes
We both with built tendencies to organize incoming sensory info into certain ways
Perceptual constancy
The recognition that objects are constant and unchained even though sensory input about them is changing
Colour constancy
The ability to perceive an object as having relatively the same color under varying illumination conditions
Illusion can occur when this adjustment leads to a misperception of color
How do we perceive depth?
Monocular depth:
* Cues rely on one eye
* Relative size
* Texture gradient
* Overlap
* shading
* Height in field of view
* Liner perspective
Hearing
Sound :
* Is the movement of air molecules brought about by the vibration of an object
The physical aspect of sound:
* Frequency = pitch (Hz)
* Amplitude = loudness (dB)
Sensing sound
The outer ear (pinna):
* Reverse megaphone - funnels sound in toward eardrum
Eardrum (aka Tympanic membrane):
* Part of the ear that vibrates when sound waves make contact
* Transmits vibrations to middle ear
Middle ear:
* Tiny chamber containing 3 tiny bones (stirrup, anvil, hammer) that act as a mechanical amplifier
Cochela:
* Colid tube in the ear is filled with fluid that vibrates in response to sound
Basilar membrane:
* Runs through the center of the cochlea - divided into two chambers, covered wit hair cells
Hair cells:
* Tiny cells that are bent by vibration - transmit neural messages (transduction happens here)
Sociocultural influences on auditory perceptions
Culture & social life provide a framework for the interpretation of stimuli
Since wave speech experiments - what people hear depends on expectations
The multitasking brain
Bottom-up processing:
* Begins with sensory receptors
* We sense the basic features of stimuli and integrate them
Top-down processing:
* Guided by higher-level mental processes
* Previous experience and expectations are used to interpret what sense detect
Perceptual sets
Predisposition or readiness to perceive something in a particular way (top - down influence)
Experience, expectations, emotions etc.
Context effects on perception
Urecall your own perceptions in different contexts
Context helps form perception and interpretation of a situation
Emotions can sway our perceptions
Sad music predisposes us to perceive sad meanings (mourning vs. morning)
Anger increases likelihood that neutral items will be mistaken as a weapon
Worrying about panic leads to interpreting physical sensations as panic
Motives & perception
Desired objects seem closer when motivated
Closeness can increase desire
Bias & perceptions
Children as naive, and innocent, afforded certain protections
Perceptions of age can be influenced by race
264 university students involved in the study
Overestimated the age of Black children by 4.5 years (i.e., 12 à 16-year-old)
Black children over the age of 10 are judged as significantly “less innocent” than white children of the same age.
Associated with anti-Black prejudice & dehumanization
Cross-talk between senses
Many examples:
* McGurk effect
* Rubber hand illusion
Synesthesia:
* Stimulation of one’s sense evokes another
* Sounds with color, colors with taste
