Sensory and decisional components of endogenous attention are dissociable

Abstract

Endogenously cueing a stimulus for attention enhances sensory processing of the attended stimulus, and efficiently selects information from the attended stimulus for guiding behavioral decisions. Yet, it is unknown if these sensory and decisional components of endogenous attention are under the control of common, overlapping or distinct mechanisms. Here, we tested human observers in a multi-alternative visuospatial attention task with probabilistic spatial cues, whose predictive validity varied across spatial locations. Observers' behavioral choices were analyzed with a multidimensional signal detection model, derived from Bayesian decision theory. The model effectively decoupled attention's effects on perceptual sensitivity from those on decisional thresholds (bias), and revealed striking dissociations between them. Sensitivity was highest at the cued location, and not significantly different among uncued locations, suggesting a spotlight-like allocation of sensory resources at the cued location. On the other hand, bias varied systematically with endogenous cue validity, suggesting a graded distribution of decision thresholds across all locations. Cueing-induced modulations of sensitivity and bias were uncorrelated within and across subjects. Finally, bias selectively correlated with key measures of decision-making: reaction times were strongly correlated with bias, cueing-induced benefits in reaction times were correlated with bias changes independently of sensitivity changes, and subjects who exhibited higher bias, rather than higher sensitivity, toward the cued location produced more optimal behavioral decisions. Our model and findings demonstrate that endogenous cueing of attention does not engage a unitary selection mechanism, but rather involves the operation of dissociable sensory enhancement and decisional selection processes.Keywords: Top-down attention, perceptual sensitivity, decisional bias, efficient selection, signal detection theory, Bayesian decision theory, psychophysical models.2 not peer-reviewed) is the author/funder. All rights reserved. No reuse allowed without permission.The copyright holder for this preprint (which was . http://dx.doi.org/10.1101/231613 doi: bioRxiv preprint first posted online Dec. 11, 2017; Significance statementThe capacity for selective attention allows us to engage efficiently with the most important objects in the world around us. Attention affects the way we perceive important stimuli and also affects how we make behavioral decisions about these stimuli. In this study, we test human observers on a multiple alternative attention task and show that attention's effects on perceptual processing and decision-making can be dissociated. Specifically, attention's sensory effects alone are in line with the conventional notion of an attentional "spotlight".These insights are obtained with a novel Bayesian decision model, which we propose as a powerful tool for teasing apart component processes of cognitive phenomena, and could aid the search for the neural correl...

Exogenous attention facilitates performance through dissociable sensitivity and bias mechanisms

“…4D). Similar, hemifield-specific effects on biases have not been observed with endogenous cueing (38). Control analyses revealed that neither the benefits in bias at the cued location, nor the correlation of the bias between the Cu and Ip locations, could be attributed to sensory input gain or motoric response bias.…”

“…These are, in order: (i) the cued location (Cu), (ii) the location in an adjacent quadrant, ipsilateral (Ip) or (iii) contralateral (Co) to the cue, and (iv) the location in the quadrant diagonally opposite to the cue (Op). The behavioral responses in the 5x5 contingency table were analyzed with a multidimensional signal detection model, the m-ADC model (36)(37)(38), to quantify psychophysical parameters (sensitivity and bias) at each location. In Figure 1C we show a schematic of a twodimensional (2-ADC) model, for illustrative purposes, although these data were analyzed with a fourdimensional (4-ADC) model (see Methods).…”

“…To estimate sensitivity and bias from the 5x5 stimulus response contingency table, we employed a multidimensional signal detection model, the m-ADC model ( Fig. 3A) (36,38). The model is parameterized by sensitivity and criterion parameters, one set at each location (see Methods).…”

“…Our recent work (38) investigated the effects of endogenous cueing of attention, on sensitivity and bias with a four-alternative change detection task, with a stimulus configuration similar to the one used in the present study. Comparing exogenous and endogenous cueing effects on multi-alternative decision-making revealed many similarities but also certain key differences with regard to how the two types of attention operate.…”

“…Because a salient exogenous cue also suppresses visual processing of stimulus information, we designed two post-cue control conditions which permitted isolating pre-cueing attentional effects from visual interference effects of the cue. Subjects' behavior was analyzed with a recently developed multidimensional signal detection model (36)(37)(38) that permitted quantifying exogenous cueing effects on sensitivity and bias at each location. The results reveal key dissociations between sensitivity and bias changes induced by exogenous cueing, and provide mechanistic insights into how exogenous cueing systematically facilitates behavioral accuracies and reaction times by modulating sensitivity and bias.…”