Chapter 5: Sensation and Perception Flashcards
Sensation
-the stimulus-detection process that our sense organs respond to, translate, and create nerve impulses to send to the brain
Perception
-the active process of organizing stimuli inputs and deriving meaning
Stimulus detection
-a stimulus can be detected 50% of the time, the threshold of the lowest intensity that a stimulus can be detected
Signal Detection Theory
-a theory focused on factors that. influence sensory
-decision criteria: a standard of how a certain person must be before detecting it
-noticing stimuli from lower thresholds brings increased rewards
-noticing danger/punishment stimuli raises detection threshold
Difference Threshold
-the smallest difference between 2 stimuli that can be perceived 50% of the time
-Weber’s Law: to perceive a difference between any two stimuli, one must differ by a constant ratio
-this doesn’t apply to extremely high or low stimulation intensities
- eg –> the value for weight is 1/50. so if 50lbs is lifted, a difference in weight will only be detected at 51lbs
Sensory Adaptation
-the diminishing sensitivity to an unchanging stimulus
-the perception of stimuli will decrease if constantly present
The Human Eye
-Cornea: a transparent protective structure where light enters through
-Pupil: an adjustable opening that dilates to control the amount of light
-Iris: it controls the pupil’s movements
-Retina: a multi-layered tissue are the rear of the eyeball
Lens
-an elastic structure that thins or thickens to focus on near/far objects
-the perceived image is upside down, and flipped later in the retina
-the ability to see images clearly depends on the lens’ ability to focus the image directly on the retina
-myopia: nearsightedness, lens focuses image in front of retina
-hyperopia: farsightedness, lens focuses image behind retina
Photorecpetors
-rods: black and white receptors, works best in dim light
-cones: colour receptors, works best in bright light
-the retina is covered in these light-sensitive receptors
-in humans, rods are everywhere except at the fovea (direct centre of retina)
-cones decrease in concentration the further they are from the fovea
-rods and cones sends messages to the brain via bipolar cells (synaptic connections with rods and cones) and ganglion cells (axons form into optic nerve)
-cones in the fovea each have a private line to a single bipolar cell
-unlike other cones, where many are attached to a bipolar cell
-a blind spot exists where ganglion cells exit and form the optic nerve
Transduction
-the process where stimuli are translated into nerve impulses
-rods and cones use photopigments to accomplish transduction
-the absorption of light triggers release of neurotransmitters
Dark Adaption
-the progessive improvement of brightness sensitivity in dark settings
Trichromatic Theory
-there are blue, green, and red colour receptors in the retina
-all other colours are produced by a combination of wavelengths
-flaws in this theory:
-yellow is produced by red and green, yet red-green colourblind people can see yellow
-Color Afterimage: an image in different colours appears after stimulus is taken away
Opponent-Process Theory
-three combination colour receptors
-red-green, blue-yellow, black-white
-each respond to two different wavelengths
Dual Processes in colour transduction theory
-a modern theory that combines both
-cones have either blue, green, or red photopigments
-ganglion cells alternate their firing rate to support opponent-process
Colour-Deficient Vision
-dichromat: color-blind to one system (red-green)
-monochromat: completely colourblind
Analysis and Reconstruction
-optic nerve sends nerve impulses to the thalamus in the brain
-groups of neurons receive and integrate the nerve impulses
-“feature detector cells” fire selectively to specific stimuli
-some cells fire when there is a horizontal line, some when there is a certain angle
-Parallel Processing: different cells analyze stimuli and work together to create a unified image
Visual Association Process
-information analyzed and constructed in the primary visual cortex is then routed to other regions to further understand it
Audition
-the transduction system of the ear is made up of bones, membranes, and tubes
-sound waves vibrate the eardrum, which vibrates the three bones (hammer, anvil, stirrup)
-the ossicles amplifies sound waves 30 times
-Cochlea: a coiled, snail shaped tube that contains membrane tissue
-Organ of Corti: rests on the membrane, has tiny hair cells / sound receptors, which release neurotransmitters
Sound localization
-the ability to notice sound location from timing differences
Hearing loss
-conduction deafness: problems with the mechanical system, sound waves don’t transmit to the cochlea
-nerve deafness: caused by damage to receptors or the auditory nerve
Taste and smell
-taste = gustation
-smell = olfaction
-these are sensitive to chemical molecules, rather than energy
-taste buds of bitter, sour, salty, sweet receptors
-receptors of smell are long cells that project through the lining of the upper nasal cavity
-Pheromones: chemical signals found in natural body scents
Menstrual Synchrony: tendency for women who live together to have similar menstrual cycles
Skin and Body Senses
-receptors in skin and organs sense pressure, pain, warmth, cold
-mixtures of such cause other sensations like an itch
-Kinesthesis: feedback on muscle and joint’s positions to help orientation and balance
Bottom up processing
-taking individual elements and combining them into a unified perception
Top down processing
-sensory information is interpreted based on prior existing knowledge
Attention
-attention involves processes of focusing on stimuli and filtering out other incoming information
-studied through shadowing:
-participants hear two messages simultaneously
-they have to repeat one message word for word
-most are unable to repeat the other one word for word
-this is strongly influenced by nature and internal factors like motive and interest
Synesthesia
-the stimuli is one sense stimulates other senses
Gestalt Theory
-strong belief in top-down processing
-perceived stimuli is interpreted and the final result is more than what is actually there
-Figure Ground Relations: a perceptual organization where a focal stimulus is perceived only as a background of other stimuli
4 ways to interpret stimuli
1: similarity
#2: proximity
#3: closure (people tend to fill gaps themselves)
#4: continuity (forming patterns)
Perceptual Schema
-a mental representation of an image to compare it to
Perceptual Set:
-a readiness to perceive based on expectations, beliefs, emotions
Perceptual Constancies
-the ability to recognize stimulus in varying conditions
-eg –> recognizing that an open door and a closed door are both doors
-Shape Constancy: recognizing in different settings/shapes
-Brightness Constancy: recognizing in different light intensities
Depth, Distance, Movement
-the retina can only perceive the length and width (2D)
-the brain can translate information into 3D by:
#1: Monocular Depth Cues: only one eye, using light and shadow
#2: Binocular Disparity: both eyes, more accurate than one
-movement is determined relatively by other still/moving objects
-Stroboscopic Movement: an illusion that when a light is quickly shone in the dark here, then other there, it seems like it’s moving
