Individual differences in the Pd component support object-file updating as the source of the same-location cost in attentional orienting

Spatial cues that mismatch the colour of a subsequent target have recently been shown to slow responses to that target. The source of this ‘same location cost’ (SLC) is currently unknown. Two potential sources are attentional signal suppression and object-file updating. Here, we tested these accounts by reanalysing data from a previously published spatial-cueing study in which we recorded brain activity using electroencephalography (EEG), and focusing on the event-related PD component, which is thought to index attentional signal suppression. Correlating PD component amplitude with SLC magnitude gives rise to two opposing predictions. If attentional signal suppression is the source of the SLC, then the SLC should be positively correlated with PD amplitude. Alternatively, if object-file updating is the source of the SLC, the SLC should be negatively correlated with PD magnitude, as a more suppressed signal should be easier to update with subsequent target features. Forty-eight participants performed a colour-based spatial-cueing task, and showed a pattern of reaction times consistent with an SLC. Across participants, SLC and PD magnitudes were negatively correlated (r=-.41, p=.004). This finding is not compatible with an attentional suppression account of the SLC, and instead supports object-file updating as the source of the SLC.