PSYC 1101 Lecture Notes - Motion Perception, Auditory Cortex, Hair Cell
6 Jun 2018
School
Department
Course
Professor
Emily Melsky
AP Psych
2 December, 2016
Notes on Sensation and Perception
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
● Perception → the process of organizing and separating information, it allows us to
recognize meaningful objects and events
● Bottom-up processing → analysis that begins with sensory receptors and works up to
the brains integration of sensory information
● Top-down processing → information processing guided by high-level mental
processes, as when we construct perceptions drawing on our past experiences and
expectations
● Bottom-up processes details from senses, top-down interprets them
Transduction
● Senses:
○ Receive sensory info
○ Transform it into neural impulses
○ Deliver that info to the brain
● 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
Thresholds
● We are blind/deaf to some types of sound/light waves
Absolute Thresholds
● Absolute threshold → the minimum stimulus energy needed to detect a particular
stimulus 50 percent of the time
○ For sound, at the point where you can hear 50% of the time at a certain frequency
● Signal detection theory → a theory predicting how and when we detect the presence
of a faint stimulus (signal) among background stimulation (noise). Assumes that there
is no single absolute threshold and that detection depends partly on a persons
experience, expectations motivation, and alertness
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● Responses to stimuli change in different circumstances
● Subliminal → below ones absolute threshold for consciousness and awareness
● Priming → the activation, often unconsciously, of certain associations, thus
predisposing ones perception, memory, or response
Difference Thresholds
● People can detect slight differences in sounds based on their profession or relation to the
sound (mother to child’s voice)
● 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 (or jnd)
● Webers 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
● Sensory adaptation → diminished sensitivity as a consequence of constant stimulation
○ ‘Nose blind’
● Does not occur with eyes because eyes are always moving
● “We perceive the world not exactly as it is, but as how it is useful for us to perceive it.”
● Influenced how emotions are perceived
Perceptual Set
● Perceptual set → a mental predisposition to perceive one thing and not another
● How we perceive can be influenced by things we perceive beforehand
Context Effects
● Context of an event can affect how someone perceives it
Motivation and Emotion
● Cues that affect emotions, such as listening to a certain genre of music, can change how
situations are perceived
● Motives also affect how things are perceived
Vision: Sensory and Perceptual Processing
Light Energy and Eye Structures
● Eyes receive light energy and transduce it into neural messages
The Stimulus Input: Light Energy
● 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 cosmic rays to the
long pulses of radio transmission
● Hue → the dimension of color that is determined by wavelength of light; what we
know as the colors (red, green, blue, etc.)
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● 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
The Eye
● Light enters through cornea
● Pupil → the adjustable opening in the center of the eye through which light enters
● Iris → ring of muscle tissue that forms the colored part of the eye and controls the size
of the pupil
○ Responds to emotions
● 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, that contain receptor rods and
cones plus layers of neurons that begin the processing of visual information
● Accommodation → the process by which the eyes lens changes shape to focus near or
far objects on the retina
● Receptors pick up light particles and transforms them into neural impulses
Information Processing in the Eye and Brain
Retinal Processing
● Rods → retinal receptors that detect white, black, and grey; necessary for peripheral
and twilight vision when cones dont respond
● 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 sensations
● Rods and cones → chemical reaction → bipolar cells → ganglion cells → optic nerve
● 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
● Brain automatically fills blind spot
● Fovea → the central focal point in the retina around which the eyes cones cluster
● Each cone has a connection to a bipolar cell which helps relay the message to the visual
cortex
● Rods
○ Help with peripheral vision
○ Good in dim light
● Cones
○ Are for color
○ Don’t work in dim light
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Document Summary
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 separating information, it allows us to recognize meaningful objects and events. Bottom-up processing analysis that begins with sensory receptors and works up to the brain(cid:1442)s integration of sensory information. Top-down processing information processing guided by high-level mental processes, as when we construct perceptions drawing on our past experiences and expectations. Bottom-up processes details from senses, top-down interprets them. 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. We are blind/deaf to some types of sound/light waves. Absolute threshold the minimum stimulus energy needed to detect a particular stimulus 50 percent of the time.
