Feature similarity is non-linearly related to attentional selection: Evidence from visual search and sustained attention tasks

Abstract

Although many theories of attention highlight the importance of similarity between target and distractor items for selection, few studies have directly quantified the function underlying this relationship. Across two commonly used tasks—visual search and sustained attention—we investigated how target-distractor similarity impacts feature-based attentional selection. Importantly, we found comparable patterns of performance in both visual search and sustained feature-based attention tasks, with performance (response times and dʹ, respectively) plateauing at medium target-distractor distances (40°–50° around a luminance-matched color wheel). In contrast, visual search efficiency, as measured by search slopes, was affected by a much more narrow range of similarity levels (10°–20°). We assessed the relationship between target-distractor similarity and attentional performance using both a stimulus-based and psychologically-based measure of similarity and found this nonlinear relationship in both cases. However, psychological similarity accounted for some of the nonlinearities observed in the data, suggesting that measures of psychological similarity are more appropriate when studying effects of target-distractor similarities. These findings place novel constraints on models of selective attention and emphasize the importance of considering the similarity structure of the feature space over which attention operates. Broadly, the nonlinear effects of similarity on attention are consistent with accounts that propose attention exaggerates the distance between competing representations, possibly through enhancement of off-tuned neurons.

Efficient tuning of attention to narrow and broad ranges of task-relevant feature values

“…Experiment 1a suggests that participants can focus feature-based attention broadly across a range of colors quite efficiently, with relatively small costs in performance. However, one potential alternative explanation for these findings is that the decrease in performance we found is driven not just by the range of target colors, but by the correlated change in targetdistractor similarity with different ranges, which affects performance in this type of featurebased attention task (Chapman & Störmer, 2022). Because we used a circular color space, increasing the range of to-be-attended colors necessarily increases the similarity between targets and distractors (as can be seen in Figure 1B).…”

“…Recent work of ours is consistent with this interpretation. By manipulating the similarity between target and distractor items, we found that attentional selection was equally and maximally effective for distractors beyond approximately 40-50° from a target color (Chapman & Störmer, 2022), suggesting that such colors can be easily ignored by the visual system when irrelevant for a task. Compared to the current study, where colors spanning up to 120° of color space were efficiently selected, and previous research arguing that distinct targets could not be jointly selected (Liu et al, 2013;Liu & Jigo, 2017), these findings collectively suggest that a contiguous set of target features can provide a scaffold that aids attentional selection.…”

“…Nonetheless, future work could investigate the role of distractor processing more directly. One important factor would be how efficiently targets and distractors can be discriminated (Chapman & Störmer, 2022), meaning that manipulations that affect the similarity between these features or that increased the range of the distractor features may provide further insight into the flexibility of attentional focus (Duncan & Humphreys, 1989;Geng & Witkowski, 2019).…”

Sustained selective attention to chromatic information enhances visuocortical gain at the population level

“…To eliminate confounds with spatial attention, these arrays are typically spatially overlapping with an array of competing stimuli with differing hues (Andersen et al, 2008, 2009; Andersen & Müller, 2010; Bartsch et al, 2018; Müller et al, 2006, 2018; A. L. White et al, 2015). Only a few studies have also examined simultaneous attention to two colours or distraction by multiple colours (Andersen et al, 2013; Beck et al, 2012; Chapman & Störmer, 2022; Martinovic et al, 2018; Störmer & Alvarez, 2014). As such, prior work has focused on selection and competition between specific exemplars within a feature dimension such as a specific hue (Andersen et al, 2008, 2009) or orientation (Thigpen et al, 2019).…”

“…L. White et al, 2015). Only a few studies have also examined simultaneous attention to two colours or distraction by multiple colours (Andersen et al, 2013;Beck et al, 2012;Chapman & Störmer, 2022;Martinovic et al, 2018;Störmer & Alvarez, 2014). As such, prior work has focused on selection and competition between specific exemplars within a feature dimension such as a specific hue (Andersen et al, 2008(Andersen et al, , 2009 or orientation (Thigpen et al, 2019).…”