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Reading 1:. Direct Perception. X-Y eye experiment The spinning wheel, others – Is perception direct?. Air and Ground Theory. Air – items in the air in a st . line project onto the same part of the retina Ground – texture gradients, occlusion and so on come into play. Veridical perception.
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Direct Perception • X-Y eye experiment • The spinning wheel, others – • Is perception direct?
Air and Ground Theory • Air – items in the air in a st. line project onto the same part of the retina • Ground – texture gradients, occlusion and so on come into play. • Veridical perception
Optic Flow • Invariant structures • Time to contact – τ(tau) • Inverse of relative rate of expansion of image on retina • Order/control parameters?
Affordances • Warren – pi values • Ratios of leg length to stair height • Ratios of aperture width to shoulder width • Order/control parameters?
Change/development • Gradual? • Variable/discontinuous/regressions/progressions
Constraints • Newell: Organismic, Task, Environmental • Schmidt & Fitzpatrick: CNS, Action System, Environment • Walking/Crawling: preferred activity depended on current movement repertoire. • Order/control parameters?
Stepping • 8 weeks: Kick = step • 8 weeks: water = step • Leg mass: muscle vs. fat in first two months • Order/control parameters?
Reaching/Grasping • Vertical (less against gravity): • 12-19 wks showed mature (ish) reaching/grasping • Recline/supine (more against gravity): • 12-19 wks poorer coordination and less frequent movements • Overall model: reaching/grasping affected by: body orientation, arm weight, arm circumference. • Order/control parameters?
Spontaneous arm movements • Arm movements depended on posture and girth of arm
Visual Information as a constraint • Attunement • Information used changes as person matures • Implies change in perceptual circuitry with change in motor capability • Binocularity and stereopsis • Use of binocular cues increases with age • Order/control parameters?