Searching Broad Stimulus Sets psychtoolbox programs used for DAI. Project Ref Number: MR09007

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Cburt_Watcher Version 1

In the original design of the experiment we presented 92 images in a passive viewing task (some of the first participants also did a recognition task outside scanner to encourage attention). Optimal stimuli is chosen online in an iterative fashion based on maximal activity in the FFA. Each succesive generation consists of the stimuli with the greatest maximum BOLD response averaged across all previous generations.

Parameters

92 images presented for 2 secs each followed by a blank screen for 2 secs. TR 1 16 slice FFA ROIs specified in MNI space and back-normalised online.

Cburt_Watcher MVPA

MVPA is implemented online to iteratively select stimuli elicitng similarity (or dissimilarity) in the pattern of activation in fusiform and inferotemporal regions in reference to a target object.

To change the program to select the stimuli eliciting the most dissimilar pattern of activation to the reference object, open the script '/realtime/apps/experiments/pictures_mvpa/cburt_dai_adaptive_setup.m' and change the line {{{ ~21 dai.goforsimilarity=true }}}

Parameters

Participants are presented with 91 stimuli in a passive viewing task in scanner (16 slice acquisition, 1 sec TR). A target object (in this case a face) is selected as a reference from which to calculate response pattern similarity.

50% of the stimuli eliciting the most similar activation pattern to the reference stimulus are chosen for presentation across 4 successive generations. The aim is to efficiently converge on the stimuli best representing the pattern of activity in the specified region of interest.

Stimulus delivery program

Written in Psychtoolbox version 3

attachment:present_pics_v3.m