PT  - JOURNAL ARTICLE
AU  - Amanda K. Robinson
AU  - Tijl Grootswagers
AU  - Sophia M. Shatek
AU  - Jack Gerboni
AU  - Alex O. Holcombe
AU  - Thomas A. Carlson
TI  - Now you see it, now you don’t: Overlapping neural representations for the position of visible and invisible objects
AID  - 10.1101/2020.03.02.974162
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.03.02.974162
4099  - http://biorxiv.org/content/early/2020/03/03/2020.03.02.974162.short
4100  - http://biorxiv.org/content/early/2020/03/03/2020.03.02.974162.full
AB  - Humans can covertly track the position of an object, even if the object is temporarily occluded. What are the neural mechanisms underlying our capacity to track moving objects when there is no physical stimulus for the brain to track? One possibility is that the brain “fills-in” information about invisible objects using internally generated representations similar to those generated by feed-forward perceptual mechanisms. Alternatively, the brain might deploy a higher order mechanism, for example using an object tracking model that integrates visual signals and motion dynamics (Kwon et al., 2015). In the present study, we used electroencephalography (EEG) and time-resolved multivariate pattern analyses to investigate the spatial processing of visible and invisible objects. Participants tracked an object that moved in discrete steps around fixation, occupying six consecutive locations. They were asked to imagine that the object continued on the same trajectory after it disappeared and move their attention to the corresponding positions. Time-resolved decoding of EEG data revealed that the location of the visible stimuli could be decoded shortly after image onset, consistent with early retinotopic visual processes. For processing of unseen/invisible positions, the patterns of neural activity resembled stimulus-driven mid-level visual processes, but were detected earlier than perceptual mechanisms, implicating an anticipatory and more variable tracking mechanism. Monitoring the position of invisible objects thus utilises similar perceptual processes as processing objects that are actually present, but with different temporal dynamics. These results indicate that internally generated representations rely on top-down processes, and their timing is influenced by the predictability of the stimulus. All data and analysis code for this study are available at https://osf.io/8v47t/.