Unit 6

Module 16: Basic Concepts of Sensation and Perception

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

Sensory Receptors: sensory nerve endings that respond to stimuli.

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

Bottom-up processing: analysis that begins with the sensory receptors and works up to the brain’s integration of sensory information.

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

Selective attention: the focusing of conscious awareness of a particular stimulus.

Inattentional blindness: failing to see visible objects when our attention is directed elsewhere.

Change blindness: failing to notice changes in the environment; a form of inattentional blindness

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.

Psychophysics: the study of relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them.

Absolute threshold: the minimum stimulus energy needed to detect a particular stimulus 50 percent 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 there is no single absolute threshold and that detection depends partly on a person’s experience, expectations, motivation, and alertness.

Subliminal: below one’s absolute threshold for conscious awareness

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

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

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

Module 17: Influences on Perception

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

Extrasensory Perception (ESP): the controversial claim that perception can occur apart from sensory input; includes telepathy, clairvoyance, and precognition.

Parapsychology: the study of paranormal phenomena, including ESP and psychokinesis (telekinesis)

Lecture Notes 1/11

Vestibular Cortex: sends the message of dizziness after spinning, attached to your ear. Vertigo = vestibular cortex.

Olfactory (smell) is processed in the temporal and frontal lobes

Smell goes directly to the olfactory bulb instead of following all the other senses through RAS.

Bottom up processing = taking in visual processing

Top down processing = using knowledge of letters and figures to make connections.

Where you first fix your gaze and then what you make of it can determine what you see - perceptual set

the only way you can “see” is to “perceive”

Selective attention - selecting to only pay attention to the white shirts

inattentional blindness - missing the moon walking bear because attention was focused on white shirts only

Change blindness - the difficulty in noticing what is in front of us now and what was in front of us then

absolute threshold - how dim of light can you still see in? What is the lowest level of sweetness you can taste? The lowest volume that you can hear sound in?

In low light conditions, younger people can see at least a little with some sort of light. In older people, their rods have started to deteriorate. Same reason for parents telling their kids to turn on the light in a room to improve their vision.

Measured by researchers who conduct multiple tests until they can find the amount that’s perceived 50% of the time

THE MINIMUM AMOUNT OF STIMULUS THAT YOU CAN DETECT AT LEAST 50% OF THE TIME

Hit = you detected the sound (signal) and responded to it correctly

False Alarm = you responded to an absent or incorrect signal and made a mistake

Module 18: Vision - Sensory and Perceptual Processing

Wavelength: the distance from the peak of one light or sound wave to the peak of the next. Electromagnetic wavelengths vary from the short blips of gamma rays to the long pulses of radio transmission.

Hue: the dimension of color that is determined by the wavelength of light; what we know as the color names blue, green, and so forth.

Intensity: the amount of energy in a light wave or sound wave, which influences what we perceive as brightness or loudness. Intensity is determined by the waves amplitude or height.

Cornea: the eyes clear, protective outer layer, covering the pupil and iris.

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 of the eye around the pupil and controls the size of the pupil opening.

Lens: the transparent structure behind the pupil that changes shape to help focus images on the retina.

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

Accommodation: the process by which the eye’s lens changes shape to focus near or far objects on the retina.

Rods: retinal receptors that detect black, white, grey, and are sensitive to movement; necessary for peripheral and twilight vision, when cones don’t respond.

Cones: retinal receptors that are concentrated near the center of the retina and that function in daylight or in well-lit conditions. Cones detect fine detail and give rise to color sensations.

Optic Nerve: the nerve that 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.

Fovea: the central focal point in the retina, around which the eye’s cones cluster.

Table 18.1: Receptors in the Human Eye: Rod - Shaped Rods and Cone - Shaped Cones

Cones Rods

Number 6 Million 120 Million

Location in Retina Center Periphery

Sensitivity in dim light Low High

Color Sensitivity High Low

Detail Sensitivity High Low

Young-Helmholtz trichromatic (three-color) theory: the theory that the retina contains three different types of 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 (red-green, blue-yellow, 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.

Feature detectors: nerve cells in the brain’s visual cortex that respond to specific features of the stimulus such as shape, angle, or movement.

Parallel processing: processing many aspects of a problem simultaneously; the brain’s natural processing for many functions, including vision.

Module 19: Visual Organization and Interpretation

Gestalt: an organized whole. Gestalt psychologists emphasized our tendency to integrate pieces of information into meaningful wholes.

Figure-ground: the organization of the visual field into objects (the figures) that stand out from their surroundings (the ground)

Grouping: the perceptual tendency to organize stimuli into coherent groups

Depth Perception: the ability to see objects in three dimensions although the images that strike the retina are two-dimensional; allows us to judge distance

Visual Cliff: a laboratory device for testing depth perception in infants and young animals

Binocular Cue: a depth cue, such as a retinal disparity, that depends on the use of two eyes

Retinal Disparity: a binocular cue for perceiving depth. By comparing retinal images from the two eyes, the brain computes distance—the greater the disparity (difference) between the two images, the closer the object.

Monocular Cue: a depth cue, such as interposition or linear perspective, available to either eye alone.

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

Perceptual Constancy: perceiving objects as unchanging (having consistent color, brightness, shape, and size) even as illumination and retinal images change.

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

Perceptual Adaptation: the ability to adjust to changed sensory input, including an artificially displaced or even inverted visual field.

Lecture Notes 1/22

Fovea is useful for acuity (clear focused vision)

The Fovea only has one kind of photo receptor in it - CONES

Cones perceive color

Rods deteriorate over time

Shorter wavelengths are signaled to purples and blues

Longer wave lengths with lower frequencies are associated with the reds

dichromatic - only 2 colors cannot see

men are more prone to color blindness

Trichromatic can explain the after images. A hole is that people who can’t see red and green, can see yellow.

Blindsight has nothing to do with the physical eye and everything to do with the occipital lobe

Barron’s Pages 121-123 (The Other Senses)

Gate control theory explains that some pain messages have a higher priority than others. When a higher priority message is sent, the gate swings open for it and then swings shut for low priority messages

Endorphins (natural chemical pain killers produced by the body) can also swing the gate shut.

Taste buds are located on the papillae

Receptor cells are located on the olfactory bulb which gathers the messages from the olfactory receptor cells and sends that information to the brain.

The impulses from other senses, except smell, go through the thalamus first before being sent to the cortex.

Information from our sense of smell goes directly to the amygdala and then to the hippocampus

Vestibular sense tells us about how our body is oriented in space

Kinesthetic sense gives us feedback about the position and orientation of specific body parts.

Lecture 1/24

Page 5

1a - similarity, 1b - figure-ground, 1c - closure (you impose meaning where there is none), 1e - closure (your mind is filling in) 1f - proximity (because of where they lie in proximity to the others near them), 1d - continuity

Pinna - outer ear, sound travels at amplitude and frequencies

Ear Canal - going to Coachella, need to enter a pin number (pinna), after the gate let them through (sound wave), they had to walk through a canal (ear canal), have to bang a drum to get in (ear drum), after the drum we get closer to hearing a sound (hear - hammer, a - anvil, sound - stirrup)

Organ of Corti is the part of the ear where it is no longer the soundwave it is the transduction of a neural impulse

Convergence - when the eyes are coming in and crossing, focusing on the same point

Aerial perspective - when things above are hazy

Lecture 1/26

Critical period = use it or lose it.

Conduction and sensory neural hearing loss - Conduction has to do with damage to the tympanic membrane and osicle bones

Gate decides which pain we feel and which pain goes unnoticed

can be distracted by the pain by the release of endorphins

Neurological gate may be closed by acupuncture, electrical stimulation, and massage.

The transmission has to reach the brain before you can feel anything, goes for all feeling

Your spine has small and large fibers, when small ones are activated, the pain receptors are sent, when large ones are activated the gate closes.

Lamaze = breathing, pushing, and meditative distraction techniques

Taper Down Method - you only remember pain as the last couple minutes of the condition. While acclimating and “taping down” you’re not met with one extreme or another, so it hurts less.

Transduction occurs in the olfactory bulb. Scent goes into the nose through the olfactory bulb, through the limbic system

Supertaster - heritable/genetic passed down from one or both parents, if you only have one copy you’re a “medium taster”

Vestibular sense helps you maintain balance, tiny crystals located in the semicircular canal

Embodied cognition - our brain is not living in a vacuum, it is constantly interacting with what the rest of our body is experiencing. They’re not two separate things, our bodies and minds interact with each other.