Lecture 11: Motion Flashcards
What is the principle of attentional capture?
motion attracts attention
________________ is a cue that we rely on for distinguishing between event boundaries.
motion
What is an example of event boundaries?
changes in speed/acceleration of actor’s hands was a good predictor of subjective judgements about events
What is akinetopsia?
inability to perceive motion
What is real motion?
occurs when an object is physically moving
What is illusory motion (aka apparent movement, phi phenomenon)?
stationary stimuli are presented in slightly differente locations
What is induced motion?
movement of one object (usually a larger object like clouds) results in the perception of movement in another object (usually a smaller object like the moon)
What is motion aftereffect? What is an example?
observer looks at movement of object for 30-60 seconds, then a stationary object, and movement appears to occur in opposite direction from original movement (e.g. waterfall illusion)
Describe the physiology behind motion aftereffect.
- fatiguing/adapting neurons tined to motion in one direction become less sensitive compared to neurons tuned to motion in other directions
- e.g. down neurons fatigued and signals weaken, therefore up neurons generate stronger signals even at baseline
In Larsen et al.’s 2006 study comparing real and apparent motion, what were the conditions? What was the major finding?
- control condition: 2 squares in slightly different positions are briefly presented simultaneously
- real motion condition: a small square is moved back and forth
- apparent motion condition: 2 squares are quickly alternated to create illusory motion
- perception of motion in both apparent and real conditions involve SIMILAR NEURAL MECHANISMS
When an object moves, but our eyes are stationary, does the image on the retina move? Is object movement perceived?
- image on retina moves
- movement is perceived
When an object moves, and our eyes move along with it, does the image on the retina move? Is object movement perceived?
- image on retina is stationary
- movement is perceived
When an object is stationary, but our eyes move (e.g. scanning the environment), does the image on the retina move? Is object motion perceived?
- image on retina moves
- movement is NOT perceived
What is the ecological approach?
how information directly available in the environment is useful t guide perception/action
What does the term optic array refer to?
the structure created by surfaces, textures, and contours in the environment, which change as the observer moves through space
Gibson thought the optic array can be used to explain when motion is and isn’t perceived, with reference to which 2 basic kinds of changes?
- local disturbances in the optic array: objects moving relative to background
- global optic flow: overall movement of the entire optic array (i.e. without any local disturbances)
___________________ may explain why motion is perceived when an object moves whether the eyes are stationery or moving.
local disturbances in the optic array
__________________ may explain why motion is NOT perceived when the object is stationary but the eyes are moving.
global optic flow
If some aspects of the optic array change, and those changes are not uniform (e.g. some objects are covered/uncovered), will motion be perceived?
yes
If the optic array changes in a uniform way (e.g. the entirety of the optic array all moves in exactly the same way), will motion be perceived?
no
TRUE or FALSE: According to Gibson, we perceive motion when the entire field moves or remains stationary
FALSE: we perceive motion when one part of the visual scene moves relative to the rest of the scene
TRUE or FALSE: According to Gibson, we do not perceive motion when the entire field moves or remains stationary
TRUE
What is the corollary discharge theory?
movement perception depends on 3 signals: image displacement signal, motor signal, corollary discharge signal
What is the image displacement signal (IDS)?
movement of image stimulating receptors across the retina
