PSYC 3 Lecture Notes - Lecture 3: Two-Streams Hypothesis, Color Blindness, Dichromacy

• School: Irvine Valley College
• Department: Psychology
• Course: PSYC 3
• Professor: Taylor

Document Summary

Dorsal stream is how or vision for action. Ventral stream is what or vision for perception. Dorsal stream provides bottom-up visual guidance of our movements. Perception starts at the sensory input and is data-driven. Ventral stream provides perceptual top-down representations for recognition, visual thought, planning, and memory. Dorsal coding is egocentric, representations are short-lasting, processing does not lead to conscious awareness and is faster. Ventral coding is allocentric, representations are sustained over time, processing typically leads to conscious awareness and depends more on input from the fovea (detail) Optic ataxia- a condition in which there are problems with making visually guided movements in spite of reasonably intact visual perception. Grasping objects is also processed in the ventral system, not just the dorsal. The ventral system but not the dorsal system should be involved in conscious cognitive processing. The dorsal stream is important for reaching behavior. Performance on all tasks is still better with both systems intact.