Entirely irrelevant distractors can capture and captivate attention

The question of whether a stimulus onset may capture attention when it is entirely irrelevant to the task and even in the absence of any attentional settings for abrupt onset or any dynamic changes has been highly controversial. In the present study, we designed a novel irrelevant capture task to address this question. Participants engaged in a continuous task making sequential forced choice (letter or digit) responses to each item in an alphanumeric matrix that remained on screen throughout many responses. This task therefore involved no attentional settings for onset or indeed any dynamic changes, yet the brief onset of an entirely irrelevant distractor (a cartoon picture) resulted in significant slowing of the two (Experiment 1) or three (Experiment 2) responses immediately following distractor appearance These findings provide a clear demonstration of attention being captured and captivated by a distractor that is entirely irrelevant to any attentional settings of the task

Distortions of Subjective Time Perception Within and Across Senses

Background: The ability to estimate the passage of time is of fundamental importance for perceptual and cognitive processes. One experience of time is the perception of duration, which is not isomorphic to physical duration and can be distorted by a number of factors. Yet, the critical features generating these perceptual shifts in subjective duration are not understood. Methodology/Findings: We used prospective duration judgments within and across sensory modalities to examine the effect of stimulus predictability and feature change on the perception of duration. First, we found robust distortions of perceived duration in auditory, visual and auditory-visual presentations despite the predictability of the feature changes in the stimuli. For example, a looming disc embedded in a series of steady discs led to time dilation, whereas a steady disc embedded in a series of looming discs led to time compression. Second, we addressed whether visual (auditory) inputs could alter the perception of duration of auditory (visual) inputs. When participants were presented with incongruent audio-visual stimuli, the perceived duration of auditory events could be shortened or lengthened by the presence of conflicting visual information; however, the perceived duration of visual events was seldom distorted by the presence of auditory information and was never perceived shorter than their actual durations. Conclusions/Significance: These results support the existence of multisensory interactions in the perception of duration and, importantly, suggest that vision can modify auditory temporal perception in a pure timing task. Insofar as distortions in subjective duration can neither be accounted for by the unpredictability of an auditory, visual or auditory-visual event, we propose that it is the intrinsic features of the stimulus that critically affect subjective time distortions

The study design of UDRIVE: the Naturalistic Driving Study across Europe for cars, trucks and scooters

Purpose: UDRIVE is the first large-scale European Naturalistic Driving Study on cars, trucks and powered two wheelers. The acronym stands for "European naturalistic Driving and Riding for Infrastructure & Vehicle safety and Environment". The purpose of the study is to gain a better understanding of what happens on the road in everyday traffic situations. Methods: The paper describes Naturalistic Driving Studies, a method which provides insight into the actual real-world behaviour of road users, unaffected by experimental conditions and related biases. Naturalistic driving can be defined as a study undertaken to provide insight into driver behaviour during everyday trips by recording details of the driver, the vehicle and the surroundings through unobtrusive data gathering equipment and without experimental control. Data collection will take place in six EU Member States. Results: Road User Behaviour will be studied with a focus on both safety and environment. The UDRIVE project follows the steps of the FESTA-V methodology, which was originally designed for Field Operational Tests. Conclusions: Defining research questions forms the basis of the study design and the specification of the recording equipment. Both will be described in this paper. Although the project has just started collecting data from drivers, we consider the process of designing the study as a major result which may help other initiatives to set up similar studies

Ambient light modulation of exogenous attention to threat

Planet Earth’s motion yields a 50 % day–50 % night yearly balance in every latitude or longitude, so survival must be guaranteed in very different light conditions in many species, including human. Cone- and rod-dominant vision, respectively specialized in light and darkness, present several processing differences, which are—at least partially—reflected in event-related potentials (ERPs). The present experiment aimed at characterizing exogenous attention to threatening (spiders) and neutral (wheels) distractors in two environmental light conditions, low mesopic (L, 0.03 lx) and high mesopic (H, 6.5 lx), yielding a differential photoreceptor activity balance: rod > cone and rod < cone, respectively. These distractors were presented in the lower visual hemifield while the 40 participants were involved in a digit categorization task. Stimuli, both targets (digits) and distractors, were exactly the same in L and H. Both ERPs and behavioral performance in the task were recorded. Enhanced attentional capture by salient distractors was observed regardless of ambient light level. However, ERPs showed a differential pattern as a function of ambient light. Thus, significantly enhanced amplitude to salient distractors was observed in posterior P1 and early anterior P2 (P2a) only during the H context, in late P2a during the L context, and in occipital P3 during both H and L contexts. In other words, while exogenous attention to threat was equally efficient in light and darkness, cone-dominant exogenous attention was faster than rod-dominant, in line with previous data indicating slower processing times for rod- than for cone-dominant visionThis research was supported by the Grants PSI2014-54853-P and PSI2012-37090 from the Ministerio de Economía y Competitividad of Spain (MINECO

Speed has an effect on multiple-object tracking independently of the number of close encounters between targets and distractors

Multiple-object tracking (MOT) studies have shown that tracking ability declines as object speed increases. However, this might be attributed solely to the increased number of times that target and distractor objects usually pass close to each other (“close encounters”) when speed is increased, resulting in more target–distractor confusions. The present study investigates whether speed itself affects MOT ability by using displays in which the number of close encounters is held constant across speeds. Observers viewed several pairs of disks, and each pair rotated about the pair’s midpoint and, also, about the center of the display at varying speeds. Results showed that even with the number of close encounters held constant across speeds, increased speed impairs tracking performance, and the effect of speed is greater when the number of targets to be tracked is large. Moreover, neither the effect of number of distractors nor the effect of target–distractor distance was dependent on speed, when speed was isolated from the typical concomitant increase in close encounters. These results imply that increased speed does not impair tracking solely by increasing close encounters. Rather, they support the view that speed affects MOT capacity by requiring more attentional resources to track at higher speeds

Searching for the Majority: Algorithms of Voluntary Control

Voluntary control of information processing is crucial to allocate resources and prioritize the processes that are most important under a given situation; the algorithms underlying such control, however, are often not clear. We investigated possible algorithms of control for the performance of the majority function, in which participants searched for and identified one of two alternative categories (left or right pointing arrows) as composing the majority in each stimulus set. We manipulated the amount (set size of 1, 3, and 5) and content (ratio of left and right pointing arrows within a set) of the inputs to test competing hypotheses regarding mental operations for information processing. Using a novel measure based on computational load, we found that reaction time was best predicted by a grouping search algorithm as compared to alternative algorithms (i.e., exhaustive or self-terminating search). The grouping search algorithm involves sampling and resampling of the inputs before a decision is reached. These findings highlight the importance of investigating the implications of voluntary control via algorithms of mental operations

Gaze following in multiagent contexts: Evidence for a quorum-like principle

Research shows that humans spontaneously follow another individual’s gaze. However, little remains known on how they respond when multiple gaze cues diverge across members of a social group. To address this question, we presented participants with displays depicting three (Experiment 1) or five (Experiment 2) agents showing diverging social cues. In a three-person group, one individual looking at the target (33% of the group) was sufficient to elicit gaze-facilitated target responses. With a five-person group, however, three individuals looking at the target (60% of the group) were necessary to produce the same effect. Gaze following in small groups therefore appears to be based on a quorum-like principle, whereby the critical level of social information needed for gaze following is determined by a proportion of consistent social cues scaled as a function of group size. As group size grows, greater agreement is needed to evoke joint attention

EEG Correlates of Attentional Load during Multiple Object Tracking

While human subjects tracked a subset of ten identical, randomly-moving objects, event-related potentials (ERPs) were evoked at parieto-occipital sites by task-irrelevant flashes that were superimposed on either tracked (Target) or non-tracked (Distractor) objects. With ERPs as markers of attention, we investigated how allocation of attention varied with tracking load, that is, with the number of objects that were tracked. Flashes on Target discs elicited stronger ERPs than did flashes on Distractor discs; ERP amplitude (0–250 ms) decreased monotonically as load increased from two to three to four (of ten) discs. Amplitude decreased more rapidly for Target discs than Distractor discs. As a result, with increasing tracking loads, the difference between ERPs to Targets and Distractors diminished. This change in ERP amplitudes with load accords well with behavioral performance, suggesting that successful tracking depends upon the relationship between the neural signals associated with attended and non-attended objects

Reduced Distractibility in a Remote Culture

Background In visual processing, there are marked cultural differences in the tendency to adopt either a global or local processing style. A remote culture (the Himba) has recently been reported to have a greater local bias in visual processing than Westerners. Here we give the first evidence that a greater, and remarkable, attentional selectivity provides the basis for this local bias. Methodology/Principal Findings In Experiment 1, Eriksen-type flanker interference was measured in the Himba and in Western controls. In both groups, responses to the direction of a task-relevant target arrow were affected by the compatibility of task-irrelevant distractor arrows. However, the Himba showed a marked reduction in overall flanker interference compared to Westerners. The smaller interference effect in the Himba occurred despite their overall slower performance than Westerners, and was evident even at a low level of perceptual load of the displays. In Experiment 2, the attentional selectivity of the Himba was further demonstrated by showing that their attention was not even captured by a moving singleton distractor. Conclusions/Significance We argue that the reduced distractibility in the Himba is clearly consistent with their tendency to prioritize the analysis of local details in visual processing