12 Pages
Unlock Document

Steve Joordens

CHAPTER 6 PERCEPTION Perception rapid automatic unconscious process by which we recognize what is represented by the information provided by our sense organs BRAIN MECHANISMS OF VISUAL PERCEPTION The Primary Visual Cortex Hubel and Wiesel experimentunconscious animals with open eyes still brain activity with pictures being shown to themConcluded geography of visual field is retained in the primary visual cortex Map on brain is distorted giving most space to the centre of visual fieldMap is like mosaic made up of tilesmodules Module block of cortical tissue that receive info from same group of receptor cells 05mm07mm 150000 neurons All neurons within module receive info from the same small region of the retina Primary Cortex contains 2500 modules Each module receives info from small region of one retina it receives info from a small region of the visual field Hubel and Wiesel found neural circuits within each module analyzed various characteristics of their own particular part of the visual field that is of their receptive field portion of visual field in which the presentation of visual stimuli will produce an alternation in the firing rate of a particular neuron some detect orientation of lines width movement direction of movement color etc The Visual Association Cortex Individual modules are combined here Two Streams of Visual Analysis Visual info analyzed by primary is further analyzed by the association Investigators discovered more than two dozen distinct regions and subregions of visual cortex of a rhesus monkey Circuits of neurons analyze particular aspects of visual info and send results to other circuits which perform further analysis as it goes on more complex features are analyzed in milliseconds the process leads to perception of the scene and objects in it higher level also interact with memories Neurons in primary visual cortex send axons to region of visual association cortex that surrounds the striate cortex and divides them into two pathways ventral streamflow of info from primary visual to visual association area in the lower temporal lobe used to form perception of objects shape color orientation continues forward and ends in the inferior temporal cortex anddorsal stream flow of info from primary visual to visual association area in the parietal lobe used to form the perception of an objects location in 3d space ascends into posterior parietal cortex The Ventral Stream Perception of Form Recognition of visual patterns and identification takes place in the inferior temporal lobe here analysis of form and color are put together and 3D objects emerge Brain damage can cause category of defects known as visual agnosia Visual agnosia inability of a person to recognize the identity of an object visually caused by damage to the visual association cortex
More Less

Related notes for PSYA01H3

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.