Revisit once more the sensory storage account of visual working memory

ABSTRACT

Recent work has highlighted the role of early visual areas in visual working memory (VWM) storage and put forward a sensory storage account of VWM. Using a distractor interference paradigm, however, we previoulsy showed that the contribution of early visual areas to VWM storage may not be essential. Instead, higher cortical regions such as the posterior parietal cortex may play a more significant role in VWM storage. This is consistent with reviews of other available behavioural, neuroimaging and neurophysiology evidence. Recently, a number of studies brought forward new evidence regarding this debate. Here I review these new pieces of evidence in detail and show that there is still no strong and definitive evidence supporting an essential role of the early visual areas in VWM storage. Instead, converging evidence suggests that early visual areas may contribute to the decision stage of a VWM task by facilitating target and probe comparison. Apart from further clarifying this debate, it is also important to emphasize that whether or not VWM storage uses a sensory code depends on how it is defined, and that behavioural interactions between VWM and perception tasks do not necessarily support the involvement of sensory regions in VWM storage.

KEYWORDS:

• Visual working memory
• attention
• fMRI
• early visual areas
• posterior parietal cortex

Acknowledgement

I thank Christian Olivers and Stefan van der Stigchel for organizing this special issue of Visual Cognition on visual working memory, Christian Olivers, Surya Gayet, and two other reviewers for their detailed and valuable comments on earlier drafts of the manuscript. Y.X. was supported by a US National Institute of Health Grant (1R01EY022355 and 1R01EY030854).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1 To faithfully replicate the results of Harrison and Tong (2009) and to avoid participants carrying forward any strategy developed in the distractor present trials to the distractor absent trials, all distractor absent trials were shown before the distractor present trials. Although doing so might have subjected the distractor present trials to greater participant fatigue in the second half of the MRI scan, thereby lowering performance on these trials, we saw no behavioural performance drop or fMRI decoding drop in superior IPS for both trial type (behavioural performance were both below ceiling and around 76%). Thus, the fMRI decoding drop in early visual areas in the distractor present trials could not be attributed to a general fatigue effect.

2 Because the same participants took part in both of our two experiments, we were able to directly test the statistical significance of the decoding difference of a given brain region between our two experiments. While differences were obtained in early visual areas decoding, differences were not seen in superior IPS decoding and behavioural performance across the two experiments (see stats reported on p.153 of Bettencourt & Xu, 2016a).

Additional information

Funding

This work was supported by National Eye Institute (part of National Institute of Health): [Grant Numbers 1R01EY022355 and 1R01EY030854].