Spatial Attention and Negative Priming

Attention is what allows us to focus on the most salient aspects of our environment. Without attention or habituation, our systems would be overloaded from the constant bombardment of stimuli. With attention we are able to concentrate on the things that we want and are able to ignore others. In spatial attention, we are investigating how we are able to attend to or concentrate on relevant stimuli in our environment while ignoring distractors (sic). In an ERP based study of spatial attention and negative priming, subjects were asked to indicate a targets location while ignoring a distractor that was present in unequal proportions. Negative priming occurs when the processing of a stimulus previously ignored is inhindered in terms of error rate or reaction time.

In priming, it is assumed that previous experiences affect future experiences. Whether the stimulus has higher basal activation levels, is better encoded, has raised the overall activation level of a network or has been stored as a memory trace, all are possibilities used to explain the priming phenomenon. It is assumed that these techniques used to employ positive priming techniques are what hinder the system in a negative priming paradigm. Combining the aspect of attention, if a stimulus is to be actively processed and encoded, it takes your attention to complete, and inversely, attention to suppress the environmental noise or distractors. In negative priming it may be this active supression which explains the decline in behavioral responses.

Two leading theories hypothesize different mechanisms to explain the negative priming effect. Inhibition theory uses this supression of the response while retrieval theory supposes that it is old memory traces which interfer with the behavioral response. In order to parse apart these theories, it is necessary to look into the underlying neural behavior during a negative priming experience. Using ERP, one is able to take advantage of well known neural responses (including some that related to decision making) and good temporal resolution.