Week 2 Active Vision Flashcards
What is psychophysics?
The study of the relationship between physical stimuli and the perceptual experiences they generate.
What assumptions does psychophysics make?
There is a threshold below which no sensation is present.
There is an orderly relationship between stimulus intensity and sensation level.
What is the pre-cuing paradigm (Posner, 1980)?
A task where participants fixate on a central spot and respond to a target appearing on the left or right. Cues (central or peripheral) influence attention.
What are the two types of attention shifts demonstrated by Posner?
Endogenous (voluntary): Internally directed, e.g., following a central cue.
Exogenous (automatic): Triggered by external events, e.g., peripheral visual changes.
What is covert attention?
The ability to shift attention without moving the eyes, enhancing reaction speed and perceptual discrimination.
What are the three small eye movements during fixation?
Tremor
Drift
Microsaccades
What is the Hermann grid extinction illusion?
A phenomenon where fine resolution is required to perceive changes in local contrast; these changes may disappear in peripheral vision.
How do our eyes create a continuous visual experience?
By integrating snapshots of visual information from fixations and saccades.
What is the difference between overt and covert attention?
Overt attention: Focused on the point of fixation, with high visual resolution.
Covert attention: Can focus on a different location than the fixation point.
Why are eye movements fundamental to visual processing?
They allow us to direct the fovea (area of greatest acuity) to areas of interest and coordinate visual information with action.
What are the four types of eye movements used in action coordination?
Locate an object.
Direct fixation to an object.
Guide movements to interact with objects.
Check the state of the object.
What did Land & Lee (1994) find about eye movements during driving?
Drivers fixate the “tangent point” on the inside of a curve to navigate turns effectively.
What illusion do we experience during visual processing?
The illusion that we see the entire visual field in detail, even though only a small area is viewed in high detail at any one time.
What is the role of covert attention during eye fixations?
It is slow and linked to the planning of eye movements but does not involve sequential scanning during fixations.
