Effects of temporal and spatiotemporal cues on detection of dynamic road hazards

While driving, dangerous situations can occur quickly, and giving drivers extra time to respond may make the road safer for everyone. Extensive research on attentional cueing in cognitive psychology has shown that targets are detected faster when preceded by a spatially valid cue, and slower when preceded by an invalid cue. However, it is unknown how these standard laboratory-based cueing effects may translate to dynamic, real-world situations like driving, where potential targets (i.e., hazardous events) are inherently more complex and variable. Observers in our study were required to correctly localize hazards in dynamic road scenes across three cue conditions (temporal, spatiotemporal valid and spatiotemporal invalid), and a no-cue baseline. All cues were presented at the first moment the hazardous situation began. Both types of valid cues reduced reaction time (by 58 and 60 ms, respectively, with no significant difference between them, a larger effect than in many classic studies). In addition, observers’ ability to accurately localize hazards dropped 11% in the spatiotemporal invalid condition, a result with dangerous implications on the road. This work demonstrates that, in spite of this added complexity, classic cueing effects persist—and may even be enhanced—for the detection of real-world hazards, and that valid cues have the potential to benefit drivers on the road.

Investigating Object Files in Spatial Cueing

In spatial cueing, cues presented at target position (valid condition) can capture visual attention and facilitate responses to the target relative to cues presented away from target position (invalid condition). If cues and targets carry different features, the necessary updating of the object representation from the cue to the target display sometimes counteracts and even reverses facilitation in valid conditions, resulting in an inverted validity effect. Previous studies reached partly divergent conclusions regarding the conditions under which object-file updating occurs, and little is known about the exact nature of the processes involved. Object-file updating has so far been investigated by manipulating cue–target similarities in task-relevant target features, but other features that change between the cue and target displays might also contribute to object-file updating. This study examined the conditions under which object-file updating could counteract validity effects by systematically varying task-relevant (color), response-relevant (identity), and response-irrelevant (orientation) features between cue and target displays. The results illustrate that object-file updating is largely restricted to task-relevant features. In addition, the difficulty of the search task affects the degree to which object-file updating costs interact with spatial cueing.

The influence of display-to-display feature changes on net cueing effects: Evidence for a contribution of object-file updating

In spatial cueing, presenting a peripheral cue at the same position as a to-be-searched-for target (valid condition) facilitates search relative to a cue presented away from the target (invalid condition). It is assumed that this cueing effect reflects spatial attentional capture to the cued position that facilitates search in valid relative to invalid conditions. However, the effect is typically stronger for top-down matching cues that resemble the targets than for non-matching cues that are different from targets. One factor which could contribute to this effect is that in valid non-matching conditions, a cue-to-target colour difference could prompt an object-updating cost of the target that counteracts facilitative influences of attention capture by the valid cues (this has been shown especially in known-singleton search). We tested this prediction by introducing colour changes at target locations in valid and invalid conditions in feature search. This should compensate for selective updating costs in valid conditions and unmask the true capture effect of non-matching cues. In addition, in top-down matching conditions, colour changes at target positions in invalid conditions should increase the cueing effect, now by selective updating costs in addition to capture away from the targets in invalid conditions. Both predictions were borne out by the results, supporting a contribution of object-file updating to net cueing effects. However, we found little evidence for attentional capture by non-matching cues in feature search even when the selective cost by object-file updating in only valid conditions was compensated for.

Top-down feature-based cueing modulates conflict-specific ERP components in a Stroop-like task with equiprobable conditions

Both attention and interference processing involve the selection of relevant information from incoming signals. Studies already show that interference decreases when the target location is precued correctly using spatial cueing. Complementary, we examine the effect of feature-based attentional cueing on interference processing. We used a design with equal stimulus probabilities where no response preparation was possible in the valid condition due to a response mapping alternation from trial to trial. The color of the Stroop stimuli was precued either validly or invalidly. Electrophysiological data (EEG) from 20 human participants are reported. We expected reduced interference effects with valid cueing for behavioral data and for both Stroop-associated event-related potential (ERP) components (N450 and sustained positive potential; SP). The N450 showed a significant effect for valid trials but no effect in the invalid condition. In contrast, the SP was absent with valid cueing and present with invalid cues. These findings suggest that focused feature-based attention leads to a more effective attentional selectivity. Furthermore, the top-down influence of feature-based attention differentially affects the N450 and SP components.

Strategic Control Modulates Working Memory-Driven Attentional Capture

The current study used a naming task to investigate whether strategic control could modulate the process of attentional capture that is driven by working memory. The use of a naming task to engage working memory eliminates potential strategic perceptual resampling, which may have played a role in several previous studies. After naming a prime, participants performed a selection task in which they judged the direction of a moving target in each trial. Prime validity, which is the probability that the primes are identical to the selection targets, was manipulated across four experiments. The results showed that reaction times to the motion judgment were faster in the valid condition than in the invalid condition when the prime validity was 50% (Experiment 1A). These results occurred even in the presence of a highly informative spatial cue that predicted the target’s location (Experiment 4). A larger capturing effect was observed when the validity was 70% (Experiments 2 and 3). When the prime validity was lower than the chance level (0% in Experiment 1B; 15% in Experiments 2 and 3), a validity effect was not observed. Thus, the results suggest that there is a strong tendency for working memory to capture attention by default when there is no reason to avoid the influence of primes. When there is a reason to avoid the influence, strategic control modulates the attentional capture that is driven by working memory.

Influence of selective attention to sound in multisensory integration

We assessed the role of audiovisual integration in selective attention by testing selective attention to sound. Participants were asked to focus on one audio speech stream out of two audio streams presented simultaneously at different pitch. We measured recall of words from the cued or the uncued sentence using a 2AFC at the end of each trial. A video-clip of the mouth of a speaker was presented in the middle of the display, matching one of the two simultaneous auditory streams (50% of the time it matched the cued sentence and the rest the uncued one). In Experiment 1 the cue was 75% valid. Recall in the valid trials was better than in the invalid ones. The critical result was, however, that only in the valid condition we did find differences between audio–visual matching and audio-visually mismatching sentences. On the invalid condition these differences were not found. In Experiment 2 the cue to the relevant sentence was 100% valid, and we included a control condition where the lips didn’t match either of the sentences. When the lips matched the cued sentence performance was better than when they matched the uncued sentence or none of them, suggesting a benefit of audiovisual matching rather than a cost of mismatch. Our results indicate that attention to acoustic frequency (pitch) plays an important role in what sounds benefit from multisensory integration.

The Role of Transparency in Perceptual Grouping and Pattern Recognition

The shortest stimulus exposure time for which transparency can be seen was examined. In the first experiment, overlapping digits were presented for 120 ms and the luminance in the overlapping regions was varied. Subjects reported, in separate blocks of trials, either the apparent transparency of the digits or the identity of the digits. When the luminance was set so that one set of digits appeared to be seen through the other, recognition of the digits was high. When the luminance in the overlapping regions did not produce impressions of transparency, digit recognition was low. In the second experiment, digit identification at several stimulus durations was compared between stimuli that had luminance that was valid for transparency and stimuli that had invalid luminance. Performance was found to be higher in the valid luminance condition than in the invalid condition after as little as 60 ms exposure duration. This result suggests that the impression of transparency requires only relatively short exposure durations.