Download Modules 16-21: Sensation and Perception

Modules 16-21: Sensation and Perception
Module 16:
● Sensation- the process by which our sensory receptors and nervous system receive and
represent stimulus energies from our environment (physical)
● Perception- the process of organizing and interpreting sensory information, enabling us
to recognize meaningful objects and events (psychological)
● Bottom-up processing- analysis that begins with sensory receptors and works up to the
brain’s integration of sensory information (data-driven)
● Top-down processing- information processing guided by higher-level mental processes,
as when we construct perceptions drawing on our experience and expectations
(conceptually-driven)
● Likelihood principle- we will perceive the object that is most likely to be the cause of
our sensory stimulation
● Selective Attention- the focusing of conscious awareness on a particular stimulus
● Cocktail party effect: one’s ability to attend to only one voice among many
● Flow: so caught up in an experience that we miss out on a particular stimulus
● Inattentional blindness- failing to see visible objects when our attention is directed
elsewhere
● Change blindness- failing to notice changes in our environment
● Choice blindness: when the object of one;s preference is switched, they don’t
acknowledge the difference and tend to find explanations for this altered choice
● Transduction- conversion of one form of energy into another. In sensation, the
transforming of stimulus energies, such as sights, sounds, and smells, into neural
impulses our brain can interpret
● Our senses
1) Receive sensory stimulation often using specialized receptor cells)
2) Transform it into neural impulses
3) Deliver neural information to the brain
● Psychophysics- the study of relationship between the physical characteristics of stimuli,
such as their intensity, and our psychological experience of them
● Absolute threshold- the minimum stimulation needed to detect a particular stimulus
50% of the time
● Signal detection theory- a theory predicting how and when we detect the presence of a
faint stimulus (signal) amid background stimulation (noise). Assumes that there is no
single absolute value threshold and that detection depends partly on a person’s
experience, expectation, motivation, and alertness
● Subliminal- below one’s absolute threshold for conscious awareness
● Priming- the activation, often unconsciously, of certain associations, thus predisposing
one’s perception, memory, or response
● Difference thresholds or just noticeable differences (jnd)- the minimum difference
between two stimuli required for detection 50% of the time
● Weber’s Law- the principle that, to be perceived as different, two stimuli must differ by
a constant minimum percentage (rather than a constant amount)
● Sensory adaptation- diminished sensitivity as a consequence of constant stimulation
○ ex) nasty smells, hot showers
○ Focuses our attention on informative changes in our environment
● Habituation- your brain stops paying attention to things that don’t change. However, as
soon as that thing changes, it recaptures your attention
○ ex) noise, billboards
Module 17:
● Perceptual Set- a set of mental tendencies and assumptions that greatly affects (topdown) what we perceive.
● Extrasensory Perception (ESP): the controversial claim that perception can occur apart
from sensory input; includes:
○ Telepathy- mind-to-mind communication
○ Clairvoyance- perceiving remote events, such as a house fire in another state.
○ Precognition- Perceiving future events, such as an unexpected death in the next
month.
○ Psychokinesis- “mind over matter”- Ex. Levitating a table or influencing the role
of a die.
● Parapsychology- the study of paranormal phenomena, including ESP and psychokinesis.
Module 18:
● Our eyes receive light energy and transfer it into neural messages that our brain
then processes it to what we see.
➔ The Stimulus Input: Light Energy
● Wavelength- the distance from the peak of one light or sound wave to the peak of
the next.
● The wavelength determines the hue- the dimension of color that is determined by
the wavelength of light; we know as the color names.
● Intensity- the amount of energy in a light or sound wave, which we perceive as
brightness or loudness, determined by the wave’s amplitude.
➔ The Eye
● Light enters the eye through the cornea, which protects the eye and bends light to
provide focus.
● Then goes through the pupil- the adjustable opening in the center of the eye
through which light enters.
● Iris- a ring of muscle tissue that forms the colored portion and controls the size of
the pupil.
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● Lens- a ring of muscle tissue that forms the colored portion of the eye around the
pupil and controls the size of the pupil opening.
● Retina- the light-sensitive inner surface of the eye, containing the receptor rods
and cones plus neurons that begin the processing of visual information.
● Accommodation- process by which the eye’s lens changes shape to focus near or
far objects on the retina.
The Retina
● Rod- retinal receptors that detect black, white, and gray; necessary for peripheral
and twilight vision, when cones don’t respond.
● Cones- receptor cells that are concentrated near the center of the retina and
function in daylight or well-lit conditions. They detect fine detail and give rise to
color sensation.
● This activates the bipolar cells, that activates the ganglion cells, whose axons
twine together like the strands of rope to form the optic nerve- carries neural
impulses from the eye to the brain.
● Blind spot- the point at which the optic nerve leaves the eye, creating a “blind”
spot because no receptor cells are located there.
● Cones cluster around the fovea- the central focal point in the retina, around which
the eye’s cone cluster.
● Cones to detail and color, & rods to faint light and send combined messages.
Visual Info Processing
● Information from the retina’s neural layers goes to the visual cortex.
Feature Detection
● David Hubel & Torsten Wiesel worked on feature detectors- nerve cells in the
brain that respond to specific features of the stimulus.
● When disrupted we can’t interpret faces.
Parallel Processing
● Parallel processing- the processing of aspects of a problem simultaneously; the
brain’s natural mode of information processing, step-by-step (serial) processing of
conscious problem solving.
Color Vision
● Our threshold is low therefore it is easy to detect many colors.
● Young-Helmholtz trichromatic theory- the retina contains three different color
receptors-- one most sensitive to red, one to green, one to blue-- which, when
stimulated in combination, can produce the perception of any color.
● Opponent-process theory- the theory that opposing retinal processes enable
color vision. For example, some cells are stimulated by green and inhibited by
red.
Module 19:
Visual Organization
● Gestalt - meaning a “whole” (Ex: Necker Cube)
● In perception, the whole may exceed the sum of its parts
Form Perception
● Figure and ground - perceiving an object (the figure) as distinct from its surrounding (the
ground)
● Grouping - organizing stimuli into coherent groups
○ 3 examples: Proximity, Continuity, and Closure
Depth Perception
● Depth perception allows us to judge distance
● This depth perception was tested in infants through the visual cliff experiment
● Binocular cues - judge the distance of nearby objects w/ the use of 2 eyes
○ The greater the retinal disparity between 2 objects, the closer the object
● Monocular Cues - depth cues available to each eye separately
○ Examples: relative size, interposition, relative height, texture gradient, aerial
perspective, relative motion, linear perspective, and light & shadow
Motion Perception
● Phi Phenomenon - illusion of movement created when 2 or more adjacent lights blink on
and off in quick succession (Ex: Christmas Lights)
Perceptual Constancy
● Perceptual constancy - perceive objects as unchanging even as retinal images change
● Color Constancy - perception of consistent color even when illumination varies
● Shape Constancy - perceive objects as constant even while our retinas receive changing
items of them (Ex:Way you view a door)
● Size Constancy - perceive objects as having a constant size, even while our distance from
them varies (Ex: Our distance from a car)
○ Moon Illusion
● Context is important
Experience and Visual Perception
● Experience guides our perceptual interpretations
● People blind from birth who gained sight after surgery lack the experience to visually
recognize shapes, forms, and complete faces
● There is a critical period for some aspects of sensory and perceptual development
● Our perceptual adaptation to changed visual input makes the world seem normal again
Module 20:
Vocab:
Audition- the sense or act of hearing.
Frequency- the number of given wavelengths at any given time.
Pitch- a tone experienced in highness or lowness.
Cochlea- a coiled bony, fluid filled tube in the inner ear; sound waves traveling through the
cochlear fluid trigger nerve impulses.
Sensorineural hearing loss- hearing loss caused by damage to the cochlea’s receptor cells or to
the auditory nerves, also called nerve deafness.
Conduction hearing loss- hearing loss caused by damage to the mechanical system that
conducts sound waves to the cochlea.
Cochlear implant- a device for converting sounds into electrical signals and stimulating the
auditory nerve through electrodes threaded into the cochlea.
Place Theory- the theory that links the pitch we hear with the place where the cochlea’s
membrane is stimulated.
Frequency Theory- the theory that the rate of nerve impulses traveling up the auditory nerve
matches the frequency of a tone, thus enabling us to sense its pitch.
Key concepts:
Amplitude determines loudness
Frequency determines pitch,ex: low frequency low pitch.
Long waves have low frequency, ex: short waves have high frequency.
Sounds are measured in decibels.
How sound is turned into neural impulses
Outer ear -> auditory canal -> eardrum -> middle ear ( three bones, hammer anvil and stirrup) ->
inner ear -> Cochlea -> basilar membrane -> hair cells lining the surface. These hair cells trigger
impulses on adjacent nerve cells which form the auditory nerve and send signals to the auditory
cortex.
Simple version is vibrating air to fluid waves to electrical impulses to the brain.
Prolonged exposure to anything above 85 decibels produces hearing loss.
Brain interprets loudness on the number of activated hair cells.
Having two ears allows us to locate sounds due to the delay and difference of intensity between
ears.
People:
Herman von Helmholtz is associated with place theory.
Georg von Bekesy cut open cochleas of guinea pigs and cadavers.
Module 21:
● Skin sensations are variations of the basic four (pressure, warmth, cold, and pain.
● Nociceptors- sensory receptors that detect harmful temperatures, pressure, or chemicals.
● Ronald Melzack and Patrick Wall’s:
○ Gate-Control Theory- the theory that the spinal cord contains a neurological
“gate” that blocks pain signals or allows them to pass on to the brain. The “gate”
is opened by the activity of pain signals traveling up small nerve fibers and is
closed by activity in larger fibers or by information coming from the brain.
● Psychological Influences:
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○ Athletes can play through pain.
Socio-Cultural Influences:
○ When others are feeling pain, we tend to feel more pain.
Anosmia- people who are unable to smell.
Kinesthesia- the system for sensing the position and movement of individual body parts.
Vestibular Sense- the sense of body movement and position, including the sense of
balance. Monitors your head’s (thus your body’s) position and movement.
Sensory Interaction- the principle that one sense may influence another, as when the
smell of food influences its taste.
McGurk Effect- seeing mouth movements for “ga” while hearing “ba” we may perceive
“da”.
Embodied Cognition- in the psychological science, the influence of bodily sensations,
gestures, and other states on cognitive preferences and judgements.
Synesthesia- where one sort of sensation (such as hearing sound) produces another (such
as seeing color).