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Lecture 4

PSYC 2000 Lecture Notes - Lecture 4: Absolute Threshold, Color Vision, Retina

Course Code
PSYC 2000

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I. Sensation
a. The process of detecting physical energy (stimuli) from the environment and converting
it into neutral signals
b. Occurs when special receptors in the sense organs are activated allowing various forms
of outside stimuli to become neural signals in the brain
c. Transduction --- sensory receptors
a.i. Process of converting outside stimuli into neural activity
II. Perception
a. The process of selecting, organizing, and interpreting our sensations
b. Occurs when we give meaning to our sensation interpreting them as we can
II. Thresholds
a. Absolute
a.i. Minimum stimulation needed to detect a particular stimulus 50% of the time
a.ii. Detection
a.i.1. Observers response
b. Difference/Just Noticeable Difference
a.i. Minimum difference between two stimuli required for detection 50% if the time
b. Weber's Law
a.i. In humans, difference thresholds increase in proportion in the size of stimulus
a.ii. Two stimuli must differ by a constant minimum percentage to be perceived as
a.iii. K=^I
b. Subliminal messages
a.i. Below threshold stimuli
a.ii. Strong enough messages for our sensory receptors to pick up but not strong
enough for us to detect them
a.iii. Priming
a.i.1. Reveal that we can process some information from stimuli too weak to
recognize/detect (below absolute threshold)
a.i.2. The effect is subtle
II. Habituation
a. The tendency of the brain to stop attending to constant, unchanging information
a.i. Brain ignores stimuli that are being sensed but do not change
b. Sensory adaption
a.i. Tendency of sensory receptors to become less responsive to a stimulus that is
a.i.1. Receptors less responsive to the stimulus and therefore no longer send
signals to the brain
I. Vision
a. Micro-saccades
a.i. Constant movement of the eyes; tiny little vibrations that people do not notice
consciously; prevents sensory adaption to visual stimuli
b. Transduction
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