Common or distinct attention mechanisms for contrast and assimilation?

The ability to inhibit distractors while focusing on specific targets is crucial. In most tasks, like Stroop or priming, the to-be-ignored distractors affect the response to be more like the distractors. We call this assimilation. Yet, in some tasks, the opposite holds. Constrast occurs when the response is caused to be least like the distractors. Contrast and assimilation are opposing behavioral effects, but they both occur when to-be-ignored information affects judgments. We ask here whether inhibition across contrastive and assimilative tasks is common or distinct. Assimilation and contrast are often thought to have different underlying psychological mechanisms, and we use a correlational analysis with hierarchical Bayesian models as a test of this hypothesis. We designed tasks with large assimilation or contrast effects. The stimuli are morphed letters, and whether there is contrast or assimilation depends on whether the surrounding information is a letter field (contrast) or a word field (assimilation). Critically, a positive correlation was found-individuals who better inhibited contrast-inducing contexts also better inhibited assimilation-inducing contexts. These results indicate that inhibition is common, at least in part, across contrast and assimilation tasks.

Flexible attention allocation to visual and auditory working memory tasks: manipulating reward induces a trade-off.

Prominent roles for general attention resources are posited in many models of working memory, but the manner in which these can be allocated differs between models or is not sufficiently specified. We varied the payoffs for correct responses in two temporally-overlapping recognition tasks, a visual array comparison task and a tone sequence comparison task. In the critical conditions, an increase in reward for one task corresponded to a decrease in reward for the concurrent task, but memory load remained constant. Our results show patterns of interference consistent with a trade-off between the tasks, suggesting that a shared resource can be flexibly divided, rather than only fully allotted to either of the tasks. Our findings support a role for a domain-general resource in models of working memory, and furthermore suggest that this resource is flexibly divisible.