Term
| Real vs. Illusory movement |
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Definition
Real Movement: occurs when an object physically moves across the observers field of vision.
Apparent Movement: there is no actual movement of the object, but there is perception of movement. Television is a perfect example of this. |
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Term
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Definition
| An illusion that occurs after a person views a moving stimulus and then sees movement in the opposite direction when viewing a stationary stimulus. i.e - waterfall, guitar hero. |
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Term
| Corollary Discharge Theory |
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Definition
a) Three signals: Motor Signal (MS) - Is sent to the eye muscles when observer moves eyes. Corollary discharge signal (CDS) - a copy of the motor signal. Image Movement Signal (IMS) - image stimulates the receptors in the retina.
b) Comparator - A structure hypothesized by the corollary discharge theory of movement perception. The corollary discharge signal and the snesory movement signal meet at the comparator to determine whether movement will be perceived.
c) Use of Curare - Observer poisoned his eyes with native american toxin "curare" to find that when he tried to move his eyes a MS was sent to his eye muscles, causing a corollary discharge. However, his paralyzed eyes could not actually move so there was no image movement signal. Because only the CDS reached the comparator, the observer perceived movement. |
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Term
| Corollary Discharge Sketch |
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Definition
CDS -> comparator -> signal to cortex
IMS -> comparator -> signal to cortex
CDS+IMS -> comparator -> No Signal |
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Term
| Gibson's Ecological Theory |
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Definition
| The ecological approach to perception focuses on studying perception as it occurs in the natural environment. This approach emphasizes conncetion between perception and how a person navigates through the environment.This approach resulted as a reaction to traditional ways of studying perception. |
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Term
Optic Flow
Gradient of Flow
Focus of Expanse |
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Definition
Optic Flow - The flow of stimuli in the environment that occurs when an observer moves relative to the environment. Forward movement causes an expanding optic flow, whereas backward movement causes a contracting optic flow.
Gradient of Flow - In an optic flow pattern, a gradient is created by movement of an observer through the environment. The "gradient" refers to the fact that the optic flow is rapid in the foreground and becomes slower as distance from the observer increases.
Focus of expanse: The point in the flow pattern caused by observer movement in which there is no expansion. According to Gibson, the focus of expansion always remains centered on the observer's destination. |
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Term
| Role of vision in Balance (Lee's swinging room) |
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Definition
| In balancing, optic flow is important to consider. Lee's swinging room was built to make the walls swing/sway for experiments. Swinging the room forwards (towards a subject) creates the same optic flow that occurs as a person sways backwards. To compensate for this apparent sway, subjects sway forward, and often loose their balance. |
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Term
| Differences of the traditional methods of perception research VS the ecological method |
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Definition
| Gibson felt that the Ponzo illusion and laboratory research as a whole was to artificial and not an accurate depiction of what happens in the environment. The big difference between the two is philosophical; Gibson believes that it is important to study perception as it happens in the real world. Others counteract that the same perception ca occur in a controlled setting/environment. |
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