Fovea and Attentional Noise Bias the Perception of Object Feature Locations

Abstract

Attention is required for integrating object features, like color and spatial location. In a recent binding illusion coined foveal gravity, we found that color-location bindings were consistently misbound to locations closer to fovea in the absence of focal attention. Here we show that both higher weightings in fovea and noise generated from attentional allocation to the periphery appear to bias this incorrect perception of object features’ locations. Participants were cued with a shape at fixation and another in the periphery (either vertically or horizontally) before seeing a horizontal array of gray and colored diamonds (a pair of diamonds in each hemifield) either in line with or placed above fixation. Participants reported whether the two cues were the same or different shapes, and which two colors appeared at which of the four diamond locations. On average, participants reported the location of at least one colored diamond incorrectly on ~20% of all trials. When the peripheral cue was presented vertically (to remove potential attentional noise effects from modulating foveal gravity as this cue straddles the hemifield boundary affecting both hemifields equally), nearly all mislocalized trials had colors reported closer to fixation. When the peripheral cue was presented horizontally in only one hemifield and the diamonds were now above fixation (to remove potential foveal effects as colors shouldn’t be attracted to fovea because they are now presented in the periphery away from fovea), colors presented in the same hemifield as the cue were more likely to be mislocalized than in the opposite hemifield, and these mislocalizations were overwhelmingly towards fovea. Therefore, under instances of uncertainty, foveal locations will beat out peripheral locations for ownership of a feature; but noise from attending to a peripheral cue works in conjunction to actively increase uncertainty of that item’s location, with its location often defaulting towards fovea.