Unit 3 Perception and Action

Optic Flow

As you move through environment the world moves around you, which tells you how fast/where you're going Gradient of flow- Moves faster near OBSERVER and SLOWER FARTHER AWAY Focus of expansion- there is no flow at destination point

How perception is affected by Physiology

Bhalla and Proffitt (1999) Stand at base of a hill Estimate slant People who wore heavy backpack saw it as steeper Fatigue encumbered physical fitness Age

Hemianopia

Damage to one side of the primary visual cortex( damage to left results in blindness to right visual field)

Optic ataxia

Damage to parietal lobe (can consistently perceive objects but have difficult reaching)

Affordance

Information that indicates what an object is used for

How perception is affected by Behavior

Hitting Performance predicted the size of the baseball Golfers see the hole as larger when golfing , estimate the height to the target Fear of heights Visual Matching Size Estimation People who are fearful of heights see it as higher

Experimental evidence in monkeys and humans suggest that there is a ventral stream and a dorsal stream within the visual system

Monkeys with damage to ventral pathway cant tell the difference between the triangle and rectangle (object discrimination) Monkeys with damage to dorsal pathway cant determine that food is next to cylinder (Landmark discrimination)

How perception is affected by morphology, Physiology, and Behavior

Morphology- Scaled Horizon Ration: A/B=Constant height to object height Reachability defines near space (Witt,Proffitt,& Epstein,2005) Object in space-reach-cannot touch object with space-reach with tool- can touch it People estimate targets as closer when holding a tool Object closer when they have a reack

Self-Produced Movement

Movement give us info which allows us to make the next move Ex: Kitten Carousel Kitten Carousel study shows this because the passive cat has less accurate visual perception than the active cat

Action Pathway

Neural pathway, extending from the occipital lobe to the parietal lobe, that is associated with neural processing that occurs when people take action. Corresponds to the where pathway.

Perception Pathway

Neural pathway, extending from the occipital lobe to the temporal lobe, that is associated with perceiving or recognizing objects. Corresponds to the what pathway.

Core principles of embodied perception

Perception relates: • Environment • Body • External • Internal State • Purpose Perception informs people about opportunity of action and their associated costs Implicit Visual Perceptions includes visually guided actions, visual control heuristics , and happens in parietal lobe Explicit Visual Perceptions includes conscious awareness of the environment and representation that happens in the temporal lobe

How affordance is important to understanding Gibson

Potential of action is part of our perception of an object

Gibsons ecological approach to perception

Putting observers in real environments instead of studies done in the lab Interactions between observer and environment

How balance is affected by visual information

Sensory Integration- Vision affects balance because we rely on our perception of the ground/surrounding to keep us balanced

Functional Dissociation

Visually guided actions - Parietal lobe - Implicit - Visual control heuristics Conscious awareness of environment - Temporal lobe - Explicit representation

Perception and Action anatomical dissociation

We have two visual streams Dorsal Pathway (where)- goes to posterior parietal cortex Ventral Pathway (What)- goes to inferior temporal cortex

embodied perception

bodies shape, function, and state influencing our perception

Visual form agnosia

damage to the temporal lobe (can perform action but cant perceive object orientation)