article review by alexander backus distributed representations meeting article review
TRANSCRIPT
Aim: Investigate whether an object-based system of scene recognition exists in LOC and/or PPA
Article review by Alexander Backus
Distributed representations meeting article review
Experimental design E1
104 scenes
208 object images (exemplars) associated with the scenes
Presented interleaved for 1s with2s ISI
Subjects silently named each scene/object
If scene representations in LOC (LO + pF) and/or PPA are built from the constituent exemplars, it is possible to classify scene-evoked patterns with combinations of object-evoked patterns.
Scene classification analysis
Results E1
Confound: for scenes, subjects might have attended serially to the single constituent objectsE2: faster stimulus presentation (150ms)
Results E2
Confound: relationship between scene- and object-evoked patterns reflect template development for object search?E3: first a block with only scenes, then a block with only objects
Results E3
Other analyses
Which common features of scenes and objects does LO encode? Visual/semantic?Classify each object category on the basis of patterns evoked by the other object category from the same context:
Train on: & , test on: &
LO primarily encodes visual features for short stimulus presentation times, but also semantic features for longer presentation times
Other analyses
Is there information outside of the ROIs?Whole-brain searchlight procedure
LO is unique among occipitotemporal visual areas in possessing an object-based scene recognition mechanism
Motor-related
LO
PPA
pF
Other analysesIs an object-based scene recognition mechanism actually used?4AFC task with briefly presented scenes (50ms)Zero, one or two of the constituent objects were obscured
Significant effect of number of objects removed on performance and RT
Scene identification falters when both of the exemplars are removed, but only if enough of the image is obscured to simultaneously affect image-based system
Conclusions
An object-based scene recognition mechanism in LO
PPA concerned with large-scale spatial featuresLO patterns are built from individual object patterns