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Chapter 3

PSY100Y5 Chapter Notes - Chapter 3: Synesthesia, Sensory System, Psychophysics

Course Code
Dax Urbszat

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PSY100 Textbook Notes: Themes and Variations of Psychology Ziyyad Ali
Chapter 3: Perception and Sensation
Sensation: is the stimulation of the sense organs (ears, eyes etc.)
Perception: is the selection, organization and interpretation of the sensory information
Synesthesia is a condition in which perceptual or cognitive activities trigger experiences
(colour or taste)
o Emotional: specific stimuli are associated with emotion
o Grapheme-colour: Words, letters, or digits are associated with colour
o Taste-touch
o Word-taste
o Sound-colour
Psychophysics: the study of how physical stimuli are translated into a psychological
Thresholds: dividing the point between energy levels that are sensed
o Sensory receptors are tuned to a particular form of energy
o JND: The minimum difference in stimulation that is just noticeable
Weber noted that the JND is a fraction of the original stimulus intensity:
the fraction is different for different senses
o Absolute: a specific type if sensory input is the minimum amount of stimulation
an organism can detect
Sensory systems require a minimum amount of energy for activation
The stimulus intensity detected 50% of the time
Signal Detection theory: the detection of stimulus involves decision processes as well as
sensory processes, which are both influenced by a variety of factors besides stimulus
We can perceive without being aware
o Subliminal Perception: the registration of sensory input without conscious
Sensory Adaption: the gradual decline in sensitivity due to prolonged stimulus
The eye detects electromagnetic radiation (light)
o Vision is necessary and functional (survival)
Allows for detection of movement
Detection of color
o 3 of the cortical lobes are involved in vision perception

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PSY100 Textbook Notes: Themes and Variations of Psychology Ziyyad Ali
The lens has muscles attached on the sides which are responsible for moving the lens
o Focuses light rays falling on the retina
The aqueous humor is the liquid between the cornea and iris
The pupil is the opening of the iris that helps regulate the amount of light that enters
the eye
The Vitreous humor the transparent jellylike tissue filling the eyeball behind the lens.
Eye movements are referred to as Saccades
o Essential to good vision
o Reduction in the voluntary movements degrades vision
The retina is the neural lining of tissue at the back of the eye
o It absorbs light
o Processes images
o Sends visual data to the brain
Optic disk is the place in the retina where the optic nerves exit the eye
Light travels through the retina to impinge on photoreceptors at the back of the eye
o Light bleaches a pigment contained within the photoreceptors:
Bleaching leads to a graded receptor potential that eventually produces
an action potential in the ganglion cell
o Cones:
found in center of retina (fovea) and are sensitive to fine detail and color
Responsible for daylight vision
About 6 million
S,M,L cones
o Rods:
found in periphery of retina and are sensitive to movement but not fine
Responsible for night vision and peripheral vision
About 100-125 million
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