Distance and ratio effects in the flanker task are due to different mechanisms

Too Tasty to Be Ignored

Recent research has shown that even non-salient stimuli (colored circles) can gain attentional weight, when they have been loaded with some value through previous reward learning. The present study examined such value-based attentional weighting with intrinsically rewarding food stimuli. Different snacks were assumed to have different values for people due to individual food preferences. Participants indicated their preferences toward various snacks and then performed a flanker task with these snacks: they had to categorize a target snack as either sweet or salty; irrelevant flanker snacks were either compatible or incompatible with the target category. Results of a linear mixed-effects model show that the effect of flanker compatibility on participants' performance (response times) increased with the participants' preference toward the flanking snacks. This shows, for the first time, that attentional weightings in a flanker task with naturalistic stimuli (snacks) are modulated by participants' preferences toward the flankers.

Spatial proximity as a determinant of context-specific attentional settings

People implicitly encode the history of conflict associated with particular contexts and use this information to modulate attention to distractors. This manifests as a reduction in the compatibility effect in mostly incompatible locations compared to mostly compatible locations, a difference termed the context-specific proportion compatibility (CSPC) effect. CSPC effects are explained by an episodic retrieval account positing that abstract attentional settings bind to contextual cues-allowing rapid, context-driven modulation of attention. The current study interrogated this binding process by testing the influence of relative spatial proximity on the association of attentional settings with particular locations. In Experiment 1, like typical CSPC paradigms, biased locations appeared near top (e.g., mostly compatible) and bottom (e.g., mostly incompatible) edges of the screen. A novel feature was the addition of two mostly compatible (above fixation) and two mostly incompatible (below fixation) locations placed within close proximity at the middle of the screen. A CSPC effect was found for outer but not middle mostly compatible and mostly incompatible locations, suggesting the attentional setting bound to the middle locations reflected the average history of conflict (i.e., 50 % compatible) for the group of middle locations. In Experiment 2, distance between middle locations was increased, allowing middle locations to group with outer locations. The CSPC effect was found for outer and middle mostly compatible and mostly incompatible locations. Results support the relative proximity hypothesis, positing that attentional settings bound to a particular location are influenced by experience within a location and relatively close neighboring locations.

The joint flanker effect and the joint Simon effect: On the comparability of processes underlying joint compatibility effects

Previous studies observed compatibility effects in different interference paradigms such as the Simon and flanker task even when the task was distributed across two co-actors. In both Simon and flanker tasks, performance is improved in compatible trials relative to incompatible trials if one actor works on the task alone as well as if two co-actors share the task. These findings have been taken to indicate that actors automatically co-represent their co-actor's task. However, recent research on the joint Simon and joint flanker effect suggests alternative non-social interpretations. To which degree both joint effects are driven by the same underlying processes is the question of the present study, and it was scrutinized by manipulating the visibility of the co-actor. While the joint Simon effect was not affected by the visibility of the co-actor, the joint flanker effect was reduced when participants did not see their co-actors but knew where the co-actors were seated. These findings provide further evidence for a spatial interpretation of the joint Simon effect. In contrast to recent claims, however, we propose a new explanation of the joint flanker effect that attributes the effect to an impairment in the focusing of spatial attention contingent on the visibility of the co-actor.

Generalization of value-based attentional priority

Attention is the mechanism by which important or salient stimuli are selected for perceptual and cognitive processing. Which stimuli are attended has important implications for effective goal-directed behaviour, survival, and well-being. A growing body of evidence suggests that reward-predicting stimuli capture attention involuntarily. In previous studies, value-based attentional priority has been observed only when the formerly reward-related stimuli themselves were presented as targets or distractors. Here we show that stimulus-reward associations learned in one task generalize to different stimuli that share a defining feature (colour) in another task. Our results reveal a broad and flexible role for reward learning in modulating attentional priority.

Adaptation to Frequent Conflict in the Eriksen Flanker Task

We examined adaptation to frequent conflict in a flanker task using event-related potentials (ERPs). A prominent model of cognitive control suggests the fronto-central N2 as an indicator of conflict monitoring. Based on this model we predicted (1) an increased N2 amplitude for incompatible compared to compatible stimuli and (2) that this difference in N2 amplitude would be less pronounced under conditions of frequent conflict (high cognitive control). In this model, adaptation to frequent conflict is implemented as modulation of early visual processing. Traditionally, variations in processing selectivity in the flanker task have been related to a zoom lens model of visual attention. Therefore, we further predicted (3) effects of conflict frequency on early visual ERP components of the event-related potential, and (4) generalization of conflict adaptation due to increased conflict frequency in the flanker task to other visuospatial tasks, intermixed within flanker task trials. Frequent conflict was associated with reduced flanker interference in response times (RTs) and error rate. Consistent with the literature, amplitude of the fronto-central N2 was larger and latency of the central P3 longer for incompatible stimuli. Both effects were smaller when conflict was frequent, supporting the notion of fronto-central N2 as indicator of conflict monitoring. Neither amplitude nor latency of the posterior P1, as index of early visual processing, was modulated by conflict frequency. Additionally, conflict frequency in the flanker task did not affect the pattern of RTs in a probe task. In sum, our results suggest that conflict adaptation operates in a task-specific manner and does not necessarily alter early information processing, that is, the spatial focus of visual attention.