Abstract
Previous research suggests that spatial reference frames mediate linguistically-driven shifts of visual attention (Gibson & Kingstone, 2006). One consequence of reference frame usage is a selection cost when attention is directed along the left/right axis but not the above/below axis (Gibson, Scheutz, & Davis, 2009). This cost is reflected in an “Opposite Compatibility Effect” (OCE) in which slower RTs are observed when distractors located along the left/right axis opposite the cued target are response-incompatible relative to when they are response-compatible. There are two possible explanations of the OCE. According to the “differential validity hypothesis,” the OCE arises because the spatial referents of “left” and “right” are less consistent than the spatial referents of “above” and “below” across discourse contexts. In this view, RTs are slower in the incompatible condition than in the compatible condition because attention is distributed more broadly in response to “left” and “right.” In contrast, according to the “differential processing hypothesis,” the OCE arises because observers are less likely to differentiate between the left and right locations than the above and below locations. In this view, RTs are slower in the incompatible condition than in the compatible condition because this is the only condition in which it is necessary to differentiate between the left and right locations (which takes additional time). The present experiments tested these two accounts by creating three different context conditions varying the necessity of differentiating between the two endpoints: the high differentiation condition (20% compatible/80% incompatible); the medium differentiation condition (50% compatible/50% incompatible); and the low differentiation condition (80% compatible/20% incompatible). Consistent with the differential validity hypothesis, the results showed that the magnitude of the OCE remained stable regardless of context.