In the grip of fear: dissociations in attentional processing of animal fearful individuals

Using a modified attention paradigm we investigated specific attentional mechanisms in processing animal feared stimuli. In this paradigm arrays of four pictures were displayed and after its disappearance from view a probe (a letter, X or P) then followed unpredictably in the location of one of the four pictures. The results showed that discriminations of probes tended to be impeded by spider stimuli, compared to snake stimuli. This effect was potentiated by high anxiety but only for those individuals fearful of spiders, since no such effect was observed for snake fearful individuals. Moreover, the discrimination of the probes was not facilitated when presented after the feared stimuli. The implications of these findings are discussed as a function of the cognitive bias involved in specific fear.

Value-driven attentional priority signals in human basal ganglia and visual cortex

Goal-directed and stimulus-driven factors determine attentional priority through a well defined dorsal frontal-parietal and ventral temporal-parietal network of brain regions, respectively. Recent evidence demonstrates that reward-related stimuli also have high attentional priority, independent of their physical salience and goal-relevance. The neural mechanisms underlying such value-driven attentional control are unknown. Using human functional magnetic resonance imaging, we demonstrate that the tail of the caudate nucleus and extrastriate visual cortex respond preferentially to task-irrelevant but previously reward-associated objects, providing an attentional priority signal that is sensitive to reward history. The caudate tail has not been implicated in the control of goal-directed or stimulus-driven attention, but is well suited to mediate the value-driven control of attention. Our findings reveal the neural basis of value-based attentional priority.

Does temporal preparation facilitate visual processing in a selective manner? Evidence from attentional capture

The present study addressed the question of whether temporal preparation influences perceptual stimulus processing in a selective manner. In three visual search experiments, we examined whether temporal preparation aids spatial selection and thus reduces distraction caused by the onset of a task-irrelevant item. In each trial, participants had to detect a target amongst five non-targets and report a basic feature of the target. In some trials, an additional task-irrelevant singleton item (abrupt onset) appeared on the screen which distracted attention away from the target. To manipulate the degree of distraction, we varied the spatial distance and the stimulus-onset asynchrony between target and singleton. Temporal preparation for the target varied by means of constant foreperiods of different lengths. Though we observed overall faster responding in the case of high temporal preparation in all three experiments, temporal preparation did not reduce spatial distraction by the abrupt onset, even when the spatial position of the target was predictable. In sum, this pattern of results does not provide support for an influence of temporal preparation on spatial selection. Instead, it indicates that temporal preparation affects early visual processing in a non-selective manner.

Enhanced distraction by magnocellular salience signals in schizophrenia

Research on schizophrenia has provided evidence of both impaired attentional control and dysfunctional magnocellular sensory processing. The present study tested the hypothesis that these impairments may be related, such that people with schizophrenia would be differentially distracted by stimuli that strongly activate the magnocellular pathway. To accomplish this, we used a visual attention paradigm from the basic cognitive neuroscience literature designed to assess the capture of attention by salient but irrelevant stimuli. Participants searched for a target shape in an array of non-target shapes. On some trials, a salient distractor was presented that either selectively activated the parvocellular system (parvo-biased distractors) or activated both the magnocellular and parvocellular systems (magno+parvo distractors). For both manual reaction times and eye movement measures, the magno+parvo distractors captured attention more strongly than the parvo-biased distractors in people with schizophrenia, but the opposite pattern was observed in matched healthy control participants. These results indicate that attentional control deficits in schizophrenia may arise, at least in part, by means of an interaction with magnocellular sensory dysfunction.

Hold the future, let the past go: attention prefers the features of future targets

Previous studies have shown that attention can be captured by task-irrelevant distractors under the guidance of attentional control settings. However, it is unknown whether people can establish an attentional control setting (ACS) for a sequence of distinct events. The present study tested that question by asking observers to expect a sequence of two colored targets in a specific order. The results show that irrelevant distractors that matched either the color of the first expected target or that of the second target captured attention. Thus observers are unable to temporarily suppress the color of the future target in their ACS. However, the temporal order of targets is still useful for guiding attention: Observers were able to abandon the color of the first target and maintain an ACS for the second one as long as there was a sufficient time interval between the two targets.

Distractors less salient than targets capture attention rather than producing non-spatial filtering costs

Distractors that are less salient than the target evoke reaction time interference in the distractor search paradigm. Here, we investigated whether this interference indeed results from spatial attentional capture or merely from non-spatial filtering costs. Target and distractor salience was manipulated parametrically and the modulation of reaction time interference by the distance between both stimuli was taken as an indicator of attentional capture. For distractors that were less salient than the target, we found distance to be predictive of reaction time interference. Moreover, this relationship was modulated by the difference in relative salience of target and distractor: the less salient the distractor was compared to the target, the weaker was the influence of distance. These results are in accordance with the sequential sampling model of salience-based selection by Zehetleitner et al. (Zehetleitner, M., Koch, A.I., Goschy, H., Müller, H.J., 2013. Salience-based selection: Interference by distractors less salient than the target. PLoS ONE 8: e52595.). This model assumes the salience map to be computed by noisy accumulation of sensory evidence. As a result, the salience map output fluctuates around its true value and less salient locations can be denoted as most salient. A distractor less salient than the target can therefore capture attention with a certain probability. We conclude that reaction time interference by less salient distractors in the distractor search paradigm is a result of attentional capture in a proportion of trials, rather than a result of non-spatial filtering costs.

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.