ch6 visual perception

sensation

transferring information

about the environment to the

brain. -seeing, hearing, touching,

smelling, and tasting.

transduction

physical energy is

transferred into neural signals.

perception

integrating and

interpreting information coming

from the senses.

light

physical energy

eye

sensory organ

receptors

rods (120 million): presence/absence of light in rest of retina; and cones (6-8 million): color, primarily in back of retina in fovea

visual pathways

rods and cones >(synapse)> bipolar cells >(synapse)> ganglion cells >(bundle together)> optic nerve > optic chasm (R and L visions cross over/switch) > thalamus > occipital lobe

• each eye processes both visual fields but each codes for half visual field

• rods= many rods synapse with a bipolar cell

• cones= not as many cones synapse with a bipolar cell

parvocellular pathway

what you see, temporal lobe

magnocellular pathway

where in space, parietal lobe

contralateral

visual info crosses over

ipsalateral

visual info stays on same side

parallel processing

simultaneous processing of two different types of info from the same input

top down processing

previous experience and expectation influences perception, memory guided

bottom up processing

basic S info is what you use to interpret perception, external S guided

saccades

fast eye movements from one point to another, each takes 25-200ms, we are “blind” to what happens during a saccade because we aren’t bringing in new visual info

fixations

saccades are separated by pauses/fixations

allocation of visual attention

attention must be interruptible, can be drawn away from one thing to another

inattentional blindness

failure to see an object even when you are looking at it because attention is directed elsewhere

bipolar cells

receive signals from rods and cones and pass them to ganglion cells

ganglion cells

receive signals from bipolar cells and send information toward the brain