Brief, prior, exposure to red decreases categorical and coordinate spatial task performance

Location information is processed through two types of spatial processing; categorical and coordinate processing. Categorical spatial relations indicate where an object is relative to another object, without regard to the metric distance between the two objects. Coordinate spatial relations indicate metric distance without regard to relative location. In human behavioral studies, the magnocellular pathway of the lateral geniculate nucleus has been implicated in coordinate spatial processing abilities. Magnocellular pathway cells (type IV) have a center surround organization, such that red light inhibits neuronal firing. In these behavioral studies, red stimuli decreases coordinate spatial processing accuracy. Prior studies also show that there is a lag between the time of visual stimulus presentation and the time of observing a neural response in the magnocellular pathway. We sought to understand whether prior presentation of red stimuli decreases coordinate spatial performance, and also examined its effects on categorical spatial performance. The results indicate that prior presentation of red stimuli decreases accuracy and perceived confidence on both the categorical and coordinate tasks. These results confirm prior findings of the association between magnocellular pathway function and coordinate spatial processing. Implications for categorical task results and associated neural pathways are discussed.