Lecture 3: Perception Flashcards
Perception
The means by which information acquired from the environment via the sense organs is transformed into experiences of objects, events, sounds, tastes, etc.
Distal stimulus
The thing you are trying to perceive
Proximal stimulus
Pattern made by distal stimulus on sensory organ
Percept
Mental representation of stimulus
Lack of correspondence
Lack of correspondence: When the percept does not correspond to the distal stimulus, ex. optical illusion
Paradoxical Correspondence
When proximal stimulus does not correspond to distal stimulus (but percept does), ex. a moving object, two object of same size at a different distance, etc.
Direct Perception
The environment provides all necessary cues, our brains are pre-wired to pick up cues, and stimulus information is almost always unambiguous
Perceptual Constancy
Our perception of an object’s features remain constant even when viewpoint (and proximal stimulus) changes
○ Perception of size does not change with distance
○ Perception of color does not change with light
○ Perception of shape does not change with angle
Constructivist Theory
Perception uses data from the world and our prior knowledge and expectations; sensory information is often ambiguous and we must rely on our prior knowledge
Bottom-Up Processing
Processing that is driven by the external stimulus rather than internal knowledge
Top-Down Processing
Processing that is driven by knowledge and expectations
Paradox of Depth Perception
Distal stimulus is 3D, projects a 2D proximal stimulus on the retina, but the percept is 3D. This is done by exploiting depth cues
Linear Perspective
Lines converge into a hypothetical point, where they are more convergent the “distance” is further, and the more divergent they are the closer that part of the image is to the viewer
Shape Cues
Shapes closest to you appear as they are, but distort when further, conveying distance. Ex. tiles close to you on the floor are more square, and those in the distance are more rectangular in your vision
Interposition
One object blocking the view of another makes the blocking object appear closer
Relative Size
An object closer to you will be bigger in your vision than one further away
Shadow Cues
We assume lights come from above
Retinal Disparity
The disparity in the retinal image on the two eyes are larger on things that are closer to the eyes compared to things further away. The brain uses how much the object moves to detect distance
Accommodation
Lens changes to get a good focus on something closer vs. further away. Lens widens when an object is closer to you, and becomes flatter for objects further
Convergence
The closer an object is to you the more your eyes cross, or converge
Agnosia
Inability to identify objects or people
Dorsal Pathway
Located in the occipital and parietal lobes, it processes location and movement; the “where” pathway
Ventral Pathway
Located in the occipital and temporal loves, it processes color, shape, and identity; the “what” pathway
Dr. P’s deficits and preserved abilities
○ Could not recognize people he knew
○ Could not identify objects
○ Could make out the abstract shapes that made up and object (i.e. 5 protrusions coming from a glove), then relate those to something he knew
○ Vision was not impaired
○ Memory was not impaired