Mapping sequences bias pRF estimates

Dr Elisa Infanti has published the work she did during her postdoc in the lab. In this, we set out to ask whether pRF estimates in human visual cortex depend on expectation, in particular the predictability of the mapping sequence used. Most visual mapping studies use ordered stimulus designs, such as rotating wedges or bars sweeping across the visual field in a regular fashion. Some previous work has compared this to randomised designs and often this results in some differences in the parameter estimates. However, nobody has explicitly looked at whether the predictability of the stimulus matters.

She manipulated predictability in various ways: training participants to recognise a regular sequence of non-adjacent stimulus locations, or simply by cueing them to the location of the next stimulus. She then compared these designs to traditional orderly sequences or to completely random designs. While there are considerable differences in pRF size estimates between random and orderly sequences, our results suggest that predictability does not affect pRF estimates. Interestingly, whether ordered sequences yield large or smaller pRF sizes than random ones, depends on other parameters, such as the cycle duration and/or the stimulus width.


Infanti, I, & Schwarzkopf, DS (2020). Mapping sequences can bias population receptive field estimates. NeuroImage 116636 Early online.


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