Chapter 3: Perception Distinction between sensation (stimulus detection) and perception (the interpretation of sensory information) Other important concepts: subliminal perception (perceiving a stimulus without awareness), change blindness (failure to consciously detect a change in a scene), blindsight (patients with brain damage cannot consciously experience objects in their blind area but can still make judgments about them), backwards masking (second stimulus masks the first, if presented fast enough) According to Gibson, perception is intricately tied to our environment: Ecological Optics o Ambient optical array contains all visual information from any vantage; this info can change as we move around o We use gradient of texture density, topological breakage , and scatter reflection as clues to our visual surroundings o As the observer moves, the entire AOA undergoes changes/transformations optic flow field (parallax) Patten & Object recognition (ability to recognize an event is an instance of a category of event); many theories of how we do this:
1. Template Matching/Prototype Theory 2. Feature Detection ( Selfridge’s Pandemonium Model ) 3. Recognition by Components ( Biederman’s geons ) Context can also influence our perception (Ex. Moon illusion )- we use contextual cues from the environment to determine size of objects o Letters in context (word superiority & jumbled word effects) o Colours in context (“What colour is that dress?” o Cross-modal context (McGurk Effect, out vision & hearing do not agree, we try to accommodate all incoming info) Feature Integration Theory (FIT) proposes that we recognize things by first extracting features pre-attentively The Gestalt Approach to perception: proposes that an examination of small components of a perceptual image does not add up to the whole o Similar elements that are close to each other tend to be grouped o The visual system tends to provide closure to figures that are almost enclosed o We’re biased to perceive good continuation in figures o Tendency toward visual organization applies also to movement- items that move together in a similar way tend to be grouped together Top down vs. bottom-up processing (also encountered during guest lecture): o Reading: good ex. of use of context in (top-down) processing When reading a paragraph, you are not paying much attention to individual marks that make up each of the letters (barely even perceive these details) Words are so familiar that we recognize them by their overall shapes instead of having to read individual letters Eye movements skip over short, familiar words
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- Winter '16
- Viara Mileva-Seitz