PS Flashcards
Which of the following are binocular cues: Retinal disparity, convergence, relative size, interposition, relative height, shading, contour, motion parallax, constancy
Retinal disparity, convergence (the rest are monocular)
Describe what happens to the inner ear muscle during a higher pitched noise? What is this an example of?
It will contract – sensory adaptation
Describe Weber’s Law and the kind of relationship that it predicts
Change in intensity / intensity = k (linear relationship) – describes the threshold at which you are able to notice a change in any sensation (just noticeable difference)
What is the difference between the absolute threshold of stimulation and the JND? What factors can the absolute threshold be affected by?
Absolute threshold is the minimum stimulus intensity required to be detected 50% of the time. The JND is the smallest difference that can be detected 50% of the time. Absolute threshold can be affected by psychological states, emotion, experience, motivation, alertness, etc.
How can the vestibular system contribute to dizziness and vertigo?
The endolymph (fluid in canal) doesn’t stop moving when we stop spinning, indicates that we are still moving to the brain which results in dizziness.
What are otolithic organs are what do they help us detect?
Utricle and saccule – help detect linear acceleration and head positioning.
Under what conditions do we use signal detection theory and for what? What are the possible outcomes?
To make decisions under conditions of uncertainty
Present yes - hit
Preset no - miss
Absent yes - false alarm
Absent no - correct rejection
What is the difference between the means of the signal and noise distributions called?
d’ : if the # of hits are > # of misses – strong signal
In signal detection theory, what determines if the observer is liberal or conservative?
C: if less that 1 (conservative) greater than 1 (liberal: always saying yes)
Describe the difference between bottom-up and top-down processing
In bottom up processing the stimulus influences our perception (processing sensory information as it comes in)
In top down processing our cognition/background info influences perception
What are the Gestalt principles?
Similarity, Pragnanz, Proximity, Continuity, Closure
What is required for visual sensation (path of visual sensory info)
Light –> neural impulse (by way of a photoreceptor)
Where does visible light lie on the spectrum on wavelengths? What are the wavelengths of the different colors?
Lies in the middle. Violet is 400 nm and red is 700 nm
Describe what happens when light hits rhodopsin
This triggers the phototransduction cascade - to turn OFF pathways (no inhibition of ON cells)
Rhodopsin changes shape –> transducin breaks off –> alpha subunit binds to PDE –> converted cGMP to GMP –> Na+ channel closes –> glutamate is not released –> ON BPCs are no longer inhibited –> activate RGCs –> sends signal from optic nerve to brain
Where are rods and cones found?
Cones are found in the fovea (color) while rods are found mostly in the periphery (black/white – more sensitive to light)
