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Evidence accumulation and the moment of recognition: dissociating perceptual decision processes using fMRI

Ploran, Elisabeth Jeannette (2008) Evidence accumulation and the moment of recognition: dissociating perceptual decision processes using fMRI. Master's Thesis, University of Pittsburgh.

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    Abstract

    Decision making can be conceptualized as the culmination of an integrative process in which evidence supporting different response options accumulates gradually over time. We used functional magnetic resonance imaging (fMRI) to investigate brain activity leading up to and during decisions about perceptual object identity. Pictures were revealed gradually and subjects signaled the time of recognition (TR) with a button press. We examined the timecourse of TR-dependent activity to determine how brain regions tracked the timing of recognition. In several occipital regions, activity increased as stimulus information increased, independently of TR, suggesting a role in lower level sensory processing. In inferior temporal (IT), frontal and parietal regions, a gradual buildup in activity peaking in correspondence with TR suggested that these regions participated in the accumulation of evidence supporting object identity. In medial frontal cortex, anterior insula/frontal operculum, and thalamus, activity remained near baseline until TR, suggesting a relation to the moment of recognition or the decision itself. The findings dissociate neural processes that function in concert during perceptual recognition decisions.


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    Item Type: University of Pittsburgh ETD
    ETD Committee:
    ETD Committee TypeCommittee MemberEmail
    Committee ChairWheeler, Mark Ewheelerm@pitt.edu
    Committee MemberReichle, Erikreichle@pitt.edu
    Committee MemberFiez, Juliefiez@pitt.edu
    Committee MemberWarren, Tessatessa@pitt.edu
    Title: Evidence accumulation and the moment of recognition: dissociating perceptual decision processes using fMRI
    Status: Unpublished
    Abstract: Decision making can be conceptualized as the culmination of an integrative process in which evidence supporting different response options accumulates gradually over time. We used functional magnetic resonance imaging (fMRI) to investigate brain activity leading up to and during decisions about perceptual object identity. Pictures were revealed gradually and subjects signaled the time of recognition (TR) with a button press. We examined the timecourse of TR-dependent activity to determine how brain regions tracked the timing of recognition. In several occipital regions, activity increased as stimulus information increased, independently of TR, suggesting a role in lower level sensory processing. In inferior temporal (IT), frontal and parietal regions, a gradual buildup in activity peaking in correspondence with TR suggested that these regions participated in the accumulation of evidence supporting object identity. In medial frontal cortex, anterior insula/frontal operculum, and thalamus, activity remained near baseline until TR, suggesting a relation to the moment of recognition or the decision itself. The findings dissociate neural processes that function in concert during perceptual recognition decisions.
    Date: 04 June 2008
    Date Type: Completion
    Defense Date: 07 August 2007
    Approval Date: 04 June 2008
    Submission Date: 22 April 2008
    Access Restriction: No restriction; Release the ETD for access worldwide immediately.
    Patent pending: No
    Institution: University of Pittsburgh
    Thesis Type: Master's Thesis
    Refereed: Yes
    Degree: MS - Master of Science
    URN: etd-04222008-131443
    Uncontrolled Keywords: decision-making; decisions
    Schools and Programs: Dietrich School of Arts and Sciences > Psychology
    Date Deposited: 10 Nov 2011 14:40
    Last Modified: 30 May 2012 09:13
    Other ID: http://etd.library.pitt.edu/ETD/available/etd-04222008-131443/, etd-04222008-131443

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