22. movement Flashcards
4 reasons movement is important?
- you can see things you wouldn’t otherwise see
- high sensitivity to biological motion
- motion onset attracts attention
- animate motion also attracts attention
3 ways movement lets you see things you wouldn’t otherwise see?
1a. kinetic depth effect (structure from motion)
–> reveals 3D shape
1b. random dot kinematogram (hidden object)
1c. gradual/fuzzy contours disappear without retinal motion
Kinetic depth effect def? AKA? Explain, example?
- “structure from motion”
- Motion reveals a 3D shape that you couldn’t previously see bc there were no/little other depth cues in the scene
- Ex. on youtube –> black image contour on white background, didn’t look like anything until it started to rotate and you could see what it was
Random dot kinematogram meaning?
- an image of random dots with no defined shape in it
- a portion of the dots in a specific shape move, and you can identify the shape (ex. square)
- ex. in book was a fish blending into the sand, but you see it when it moves
Gradual contours disappear without retinal motion meaning? What didn’t it apply to?
- focus on a single spot in the center
–> eyes are usually moving at least a bit, this makes them stop as much as possible - purple fuzzy dots around the edges fade until they disappear
- purple dot with black outline stays!
DOESN’T apply to RIGID borders
–> including the grey square background
Neural explanation for gradual contours disappearing without retinal motion?
- eyes usually move –> neurons that detect edges would cross the fuzzy contours and detect them
- without movement, and no solid borders, neurons don’t see them, and they fade out
Why are we sensitive to biological motion?
- we’re social animals
- being able to detect motion is a key part of communication with other people
- communication is essential for survival
Evidence that we’re sensitive to biological motion?
- point light walker
- can detect bio motion with very low spatial frequency
- human movement is very effective in advertisements
Motion onset captures attention meaning? Evidence? Maybe reason why?
- people are very sensitive / pay attention when things START to move
- people were quickest to identify letter target when it began to move
Why? –> could be alive!
Animate motion def? Why does it capture attention? Evidence?
- Animate motion = movement by something that’s alive
- It captures your attention bc its more likely to be relevant to your survival
- people pay more attention to spot showing animate (self controlled)
How is a simple neural circuit to detect motion designed? Preferred…? (3 things)
- 2 neurons with diff. receptive fields link to one neuron (M)
- there is a delay in the connection between 1&M, but no delay between 2&M
- the delay means that the signal from 1 arrives at the same time as 2
^ this only works if the motion moves from the receptive field of 1 first and then 2 at the right speed
- M will have a preferred orientation, direction, and speed
2 types of eye movements?
- saccadic eye movements (or saccades)
- smooth pursuit eye movements
Saccadic eye movements (saccades) def?
Brief, rapid eye movements that change the focus of gaze from one location to another
Smooth pursuit eye movements def?
Eye movements made to track a moving object or to track a stationary object while the head is moving
Saccadic suppression def?
The visual system’s suppression of neural signals from the retina during saccadic eye movements
Evidence that we take eye movements into account? (Afterimage)
- bright light –> afterimage on retina
- look around the room
- after image “moves” b/c you move your eyes
- RETINAL POSITION of the afterimage CAN’T change
–> eyes (and head) signal movement, but there’s no change on retinal stimulus
–> you see movement
Eye movement experiment monkey –> what does it give support for?
- we take eye movement into account when perceiving motion
- we can distinguish between object moving / eyes still & eyes moving / object still
- retinal movement =/= perceived movement