AP PSYCH: Sensation and Perception

Vision

The Eye + Diagram

Cornea: the clear layer on the front part of the eye that protects the eye and bends light to provide focus

Pupil: small adjustable opening; where light enters

Iris: a colored muscle that dilates or constructs n response to light intensity and even to inner emotions; distinct; controls the size of the pupil opening

Retina: the light- sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information

Lens: Focuses incoming light rays into an image on the retina; transparent structure behind the pupil

Accommodation: the process by which lens focuses the rays by changing its curvature

The Process

  1. Light entering the eye triggers photochemical reactions in rods and cones at the back of the retina
  1. Chemical reaction in tun activates bipolar cells
  1. Bipolar cells then activate the ganglion cells, the axons of which converge to form the optic nerve. This nerve transmits information to the visual context(via the thalamus) in the brain.

Vocab!

Rods: retinal receptors that detect black, white, and gray; necessary to peripheral and twilight vision, when cones don't respond; share bipolar cells

Optic Nerve: when ganglion cell axons twine together like the strands of a rope

Blind Spot: where the optic nerve leaves the eye and there are no receptor cells

Cones: retinal receptor cells that are concentrated near the center of the retina and that function in daylight or in well- lit conditions. The cones detect fine detail and give rise to color sensation; each responds to their own bipolar cell

Fovea: the retina's area of central focus, where cones cluster

The Stimulus Input: Light

Wavelengths: the distance from one wave peak to the next; determines the light's hue

Intensity: the amount of energy in a light or sound wave, which we perceive as brightness or loudness, as determined by the wave's amplitude

Visual Processing

Feature Detectors: nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement; located in the occipital lobe; respond to a scene's specific features

Important People

David Hubel + Torsten Wiesel #

Parallel Processing: the processing of many aspects of a problem simultaneously; the brain's natural mode of information processing for many functions--> contrasts with the step- by- step process computers use

Color Vision

Herman von Helmholtz # #

Helmholtz- Young trichromatic(three-color) theory: the theory that 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 color

Hering # #

Opponent- Process Theory: the process theory that opposing retinal processes(red- green, yellow- blue, white- black) enable color vision. For example, some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green

Visual Organization(gestalt: an organized whole; our tendency to organize pieces of info into a meaningful whole)

Form Perception

Figure and Ground: distinguishing an object(the figure) from it's surroundings(the ground); always organized as a figure seen against the ground

Grouping: when our minds bring order and form to a stimulus

Proximity: grouping nearby figures together

Continuity: perceiving smooth continuous patterns rather than discontinuous ones

Closure: filling in gaps to create a complete, whole object

Depth Perception: enables us to estimate an objects distance

Eleanor Gibson and Richard Walk(visual cliff experiments) #

Binocular Cues: using both eyes to determine depth

Retinal Disparity: difference between two images

Monocular Cues: depth cues available to each eye separately

Relative Height: we perceive objects higher in our field of vision as farther away

Relative Motion: when stable objects appear to move; when you're moving and you fixate on a point(the fixation point) objects in from of the point will appear to move backwards

Relative Size: as object that looks smaller is perceived as farther away

Interposition: if one object partially blocks our view of another, we perceive it as closer

Linear Perspective: when parallel lines appear to meet in the distance; the sharper the angle of convergence the greater the perceived distance

Light and Shadow: shading produces a sense of depth consistent with our assumption that light comes from above

Motion Perception: usually perceived as shrinking objects are retreating and enlarging objects are approaching

Phi Phenomenon: an illusion of movement created when two or more adjacent lights blink on and off in quick succession

Perpetual Constancy: perceiving objects as unchanging(having consistent shapes, size, brightness, and color) even as illumination and retinal image change

Color and Brightness Constancy

Color Constancy: perceiving familiar objects as having consistent color, even if changing illumination alters the wave-lengths reflected by the object

Brightness Constancy(aka Light Constancy: when we perceive an object as having constant brightness even when it's illumination varies

Relative Luminance: the amount of light an object reflects relative to it's surroundings

Shape and Size Constancies

Shape Constancy: perception of the form of familiar objects as constant even whule our retinas receive changing images of them

Size Constancy: perception of an object as having a constant size while our distance from them varies

Visual Interpretations

We learn perception(Weisel's experiment with the cats)

Perceptual Adaptation: in vision, the ability to adjust to an artificially displaced or even inverted visual field

Hearing

The Stimulus Input: Sound Waves

Amplitude: determines the loudness

Frequency: determines the pitch

Long wave- low frequency, low pitch

Short waves- high frequency, high pitch

The Ear + Diagram

Middle Ear: the chamber between the eardrum and the cochlea containing three tiny bones(hammer, anvil, and stirrup) that concentrates the vibrations of the eardrum on the cochlea's oval window

Cochlea: a coiled, bony fluid filled tube in the inner ear; sound waves traveling through the cochlear fluid trigger nerve impulses

Inner Ear: the innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs

Hair Cells: when motion moves these cells they trigger impulses in adjacent nerve cells

Auditory Nerve: formed from nerve cells and send neural messages to the auditory cortex in the brains temporal lobes

Hearing Loss + Diagram

Sensorineural Hearing Loss: hearing loss caused by damage to the cochlea's receptor cells or to the auditory nerves; also called nerve deafness; damage to sensorial cells aka hair cells

Conduction Hearing Loss: hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea; blockage

The Process

  1. Sound waves enter via the outer ear and travel down the auditory canal to the eardrum
  1. The three bones pick up the vibrations and transfer them to the cochlea, aka a snail shaped membrane in the inner ear
  1. The fluid in the cochlea membrane jostles as a result of the vibrating of the membrane. This triggers the basilar membrane, which bends the hair cells lining the surface
  1. Hair cell movements trigger nerve cells, which form the auditory nerve
  1. Information is transfered from the auditory nerve to the auditory cortex in the brains temporal lobe

Detected based on the number of hair cells vibrating

Perceiving Pitch

Place Theory: in hearing, the theory that links the pitch we hear with the place where the cochlea's membrane is stimulated(DOESN'T EXPLAIN HOW WE HEAR LOW PITCHED FREQUENCY)

Frequency Theory: in hearing, 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(DOESN'T EXPLAIN HOW WE HEAR HIGH PITCHED FREQUENCY)

The Volley Principle: neural cells can alternate firing

Touch: mix of pressure, warmth, cold, and pain

Pain

Understanding Pain

Biological Influences

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

Ronald Melzack + Patrick Wall #

Controlling Pain

Nociceptors: sensory receptors that detect hurtful temperatures, pressure, or chemicals

Psychological Influences

Memories of pain often only recall the pain's peak moments and how much pain they felt at the end

Social- Cultural Influences

We tend to perceive more pain when others are experiencing pain

Main Points

  1. Activity in spinal cord's large and small fibers
  1. Genetic differences in endorphin production
  1. Brains interpretation of CNS activity

Main Points

  1. Attention to pain
  1. Learning based on experience
  1. Expectations

Main Points

  1. Presence of others
  1. Empathy for others' pain
  1. Cultural expectations

Mind over matter

Taste: taught through sweet, sour, salty, bitter, unami

Sensory Interaction: the principle that one sense may influence another, as when the smell of food influences its taste

Harry McGurk

The McGurk Effect: a perceptual phenomenon that demonstrates an interaction between hearing and vision in speech perception. #

Embodied Cognition: in psychological science, the influence of bodily sensations, gestures, and other states on cognitive preferences and judgements

Smell

Basic Principles of Sensation and Perception

Vocab!!!!

Sensation: the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment

Perception: the process of organizing and interpreting sensory information enabling us to recognize meaningful objects and events

Bottom- Up Processing: starts at the sensory receptors and works up to higher levels of processing

Top- Down Processing: information processing guided by higher- level mental processes, as when we construct perceptions drawing on our experience and expectations

Transduction: conversion of one form of energy into another. In sensation, the transforming of stimulus energies, such as sight, sounds, and smells, into neural impulses our brain can interpret

  1. Receive sensory stimulus
  1. Transform that stimulus into neural impulses
  1. Deliver neural information to the brain

Thresholds

Absolute Threshold: the minimum stimulation needed to detect a particular stimulus 50% of the time

Gustav Fechner #

Signal Detection Theory: a theory predicting how and when we detect the presence of a faint stimulus amid background stimulation. Assumes there is no single absolute threshold and that detection depends partly on a person's experience, expectation, motivation, and alertness

Subliminal: below one's absolute threshold for conscious awerness

Priming: the activation, often unconsciously, of certain associations thus predisposing one's perception, memory, or response

Difference Threshold: the minimum difference between two stimuli required for detection 50 percent of the time. We experience the difference threshold as just a noticeable difference

Ernst Weber #

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: diminishes sensitivity as a consequence of constant stimulation

Perceptual Set: a mental predisposition to perceive one thing and not the other