Processing references in context: when the polar bear does not meet a polar bear.

Discourse understanding is hampered when missing or conflicting context information is given. In four experiments, we investigated what happens (a) when the definite determiner "the," which presupposes existence and uniqueness, does not find a unique referent in the context or (b) when the appropriate use of the indefinite determiner is violated by the presence of a unique referent (Experiment 1 and Experiment 2). To focus on the time-course of processing the uniqueness presupposition of the definite determiner, we embedded the determiner in different sentence structures and varied the context (Experiment 3 and Experiment 4). Reading time served as an index of processing difficulty in a word-by-word self-paced reading task and acceptability judgments provided hints for a possible repair of a presupposition violation. Our results showed that conflicting and missing context information lowered acceptability ratings and was associated with prolonged reading times. The pattern of results differed depending on the nature of the presupposition (Experiments 1 and 2) and whether supplementing missing context information was possible (Experiment 3 and Experiment 4). Our findings suggest that different cognitive processes come into play when interpreting presuppositions in order to get a meaningful interpretation of a discourse.

Temporal preparation accelerates spatial selection by facilitating bottom-up processing.

Temporal preparation facilitates spatial selection in visual search. This selection benefit has not only been observed for targets, but also for task-irrelevant, salient distractors. This result suggests that temporal preparation influences bottom-up salience in spatial selection. To test this assumption, we conducted an event-related-potential (ERP) study in which we measured the joint effect of temporal preparation and target salience on the N2pc as an index of spatial selection and the N1 as an index of perceptual discrimination. To manipulate target salience, we employed two different setsizes (i.e., a small or large number of homogeneous distractors). To manipulate temporal preparation, we presented a warning signal before the search display and we varied the length of the interval (foreperiod) between warning signal and search display in different blocks of trials (constant foreperiod paradigm). Replicating previous results, we observed that the N1 and the N2pc arose earlier in case of good temporal preparation. Importantly, the beneficial effect on the N2pc onset latency was stronger when the target salience was initially low (i.e., small setsize). This result provides evidence that temporal preparation influences bottom-up processing and, thereby, facilitates spatial selection.

Reduction of temporal uncertainty facilitates stimulus-driven processes in spatial selection.

Previous studies have shown that the reduction of temporal uncertainty facilitates target selection in visual search. We investigated whether this beneficial effect is caused by an effect on stimulus-driven processes or on goal-driven processes in spatial selection. To discriminate between these processes, we employed a visual search task in which participants searched for a shape target while ignoring a color singleton distractor. As an index of stimulus-driven processes, we measured the N2pc evoked by the singleton distractor (ND). As indices of goal-driven processes, we measured the N2pc evoked by the target (NT) and the distractor positivity (PD) evoked by the singleton distractor, respectively. We observed that reducing temporal uncertainty modulated the amplitude of ND and the onset latency of the NT, but did not modulate the amplitude of the PD. These results are consistent with the view that a reduction of temporal uncertainty influences non-selective, stimulus-driven processes in spatial selection.

Illusory size determines the perception of ambiguous apparent motion.

The visual system constructs perceptions based on ambiguous information. For motion perception, the correspondence problem arises, i.e., the question of which object went where. We asked at which level of processing correspondence is solved - lower levels based on information that is directly available in the retinal input or higher levels based on information that has been abstracted beyond the input directly available at the retina? We used a Ponzo-like illusion to manipulate the perceived size and separations of elements in an ambiguous apparent motion display. Specifically, we presented Ternus displays - for which the type of motion that is perceived depends on how correspondence is resolved - at apparently different distances from the viewer using pictorial depth cues. We found that the perception of motion depended on the apparent depth of the displays, indicating that correspondence processes utilize information that is produced at higher-level processes.

Temporal attention boosts perceptual effects of spatial attention and feature-based attention.

Temporal attention, that is, the process of anticipating the occurrence of a stimulus at a given time point, has been shown to improve perceptual processing of visual stimuli. In the present study, we investigated whether and how temporal attention interacts with spatial attention and feature-based attention in visual selection. To monitor the influence of the three different attention dimensions on perceptual processing, we measured event-related potentials (ERPs). Our participants performed a visual search task, in which a colored singleton was presented amongst homogenous distractors. We manipulated spatial and feature-based attention by requiring participants to respond only to target singletons in a particular color and at a to-be-attended spatial location. We manipulated temporal attention by means of an explicit temporal cue that announced either validly or invalidly the occurrence of the search display. We obtained early ERP effects of spatial attention and feature-based attention at the validly cued but not at the invalidly cued time point. Taken together, our results suggest that temporal attention boosts early effects of spatial and feature-based attention.

How voluntary spatial attention influences feature biases in object correspondence.

Our visual system is able to establish associations between corresponding images across space and time and to maintain the identity of objects, even though the information our retina receives is ambiguous. It has been shown that lower level factors-as, for example, spatiotemporal proximity-can affect this correspondence problem. In addition, higher level factors-as, for example, semantic knowledge-can influence correspondence, suggesting that correspondence might also be solved at a higher object-based level of processing, which could be mediated by attention. To test this hypothesis, we instructed participants to voluntarily direct their attention to individual elements in the Ternus display. In this ambiguous apparent motion display, three elements are aligned next to each other and shifted by one position from one frame to the next. This shift can be either perceived as all elements moving together (group motion) or as one element jumping across the others (element motion). We created a competitive Ternus display, in which the color of the elements was manipulated in such a way that the percept was biased toward element motion for one color and toward group motion for another color. If correspondence can be established at an object-based level, attending toward one of the biased elements should increase the likelihood that this element determines the correspondence solution and thereby that the biased motion is perceived. Our results were in line with this hypothesis providing support for an object-based correspondence process that is based on a one-to-one mapping of the most similar elements mediated via attention.

The role of object history in establishing object correspondence.

Our visual system establishes correspondence between objects and thus enables us to perceive an object, like a car on the road, as moving continuously. A central question regarding correspondence is whether our visual system uses relatively unprocessed image-based information or further processed object-based information to establish correspondence. While it has been shown that some object-based attributes, such as perceived lightness, can influence correspondence, manipulating object-based information typically involves at least minimal changes of image-based information as well, making it difficult to clearly distinguish between the two levels. To avoid this confound, we manipulated object-based information prior to the task in which we measured correspondence. We used 3-element Ternus displays to assess correspondence. These are ambiguous apparent-motion displays that, depending on how correspondence is solved, are perceived as either one element jumping across the others or as all three elements moving together as a group. We manipulated object-based information by presenting one of two object histories prior to the Ternus display. In one, they moved or changed luminance independently, and thus appeared independent from each other. In the other, the elements moved or changed their luminance all together and thus appeared grouped with each other. We found that the object history did influence how the Ternus displays were perceived, thereby confirming that object-based information alone can be used as a basis for establishing correspondence in line with object-based theories of correspondence.

Multidimensional selection by temporal attention and feature-based attention: Evidence from event-related potentials.

Numerous studies have shown that temporal attention plays an important role in selective attention. The present study used the event-related potential (ERP) to investigate how temporal attention modulates effects of feature-based attention in visual selection when both dimensions are task-relevant. We combined a modified temporal cueing paradigm with a feature-based attention task. In each trial, either a valid or an invalid temporal cue announced a short or long foreperiod (FP). After each FP, a visual stimulus in one of two colors was presented. Participants were instructed to respond only if the stimulus had a specific color and followed the cued FP. We observed ERP amplitude modulations due to feature-based attention at different processing levels. Importantly, feature-based attention effects were modulated by temporal attention. These results suggest that temporal attention not only facilitates stimulus processing on its own but also serves as a selection mechanism that can modulate stimulus processing in other dimensions.

Discourse management during speech perception: A functional magnetic resonance imaging (fMRI) study.

Discourse structures enable us to generate expectations based upon linguistic material that has already been introduced. We investigated how the required cognitive operations such as reference processing, identification of critical items, and eventual handling of violations correlate with neuronal activity within the language network of the brain. To this end, we conducted a functional magnetic resonance imaging (fMRI) study in which we manipulated spoken discourse coherence by using presuppositions (PSPs) that either correspond or fail to correspond to items in preceding context sentences. Definite and indefinite determiners were used as PSP triggers, referring to (non-) uniqueness or (non-) existence of an item. Discourse adequacy was tested by means of a behavioral rating during fMRI. Discourse violations yielded bilateral hemodynamic activation within the inferior frontal gyrus (IFG), the inferior parietal lobe including the angular gyrus (IPL/AG), the pre-supplementary motor area (pre-SMA), and the basal ganglia (BG). These findings illuminate cognitive aspects of PSP processing: (1) a reference process requiring working memory (IFG), (2) retrieval and integration of semantic/pragmatic information (IPL/AG), (3) cognitive control of inconsistency management (pre-SMA/BG) in terms of "successful" comprehension despite PSP violations at the surface. These results provide the first fMRI evidence needed to develop a functional neuroanatomical model for context-dependent sentence comprehension based on the example of PSP processing.

In touch with mental rotation: interactions between mental and tactile rotations and motor responses.

Although several process models have described the cognitive processing stages that are involved in mentally rotating objects, the exact nature of the rotation process itself remains elusive. According to embodied cognition, cognitive functions are deeply grounded in the sensorimotor system. We thus hypothesized that modal rotation perceptions should influence mental rotations. We conducted two studies in which participants had to judge if a rotated letter was visually presented canonically or mirrored. Concurrently, participants had to judge if a tactile rotation on their palm changed direction during the trial. The results show that tactile rotations can systematically influence mental rotation performance in that same rotations are favored. In addition, the results show that mental rotations produce a response compatibility effect: clockwise mental rotations facilitate responses to the right, while counterclockwise mental rotations facilitate responses to the left. We conclude that the execution of mental rotations activates cognitive mechanisms that are also used to perceive rotations in different modalities and that are associated with directional motor control processes.

The influence of object similarity and orientation on object-based cueing.

Responses to targets that appear at a noncued position within the same object (invalid-same) compared to a noncued position at an equidistant different object (invalid-different) tend to be faster and more accurate. These cueing effects have been taken as evidence that visual attention can be object based (Egly, Driver, & Rafal, Journal of Experimental Psychology: General, 123, 161-177, 1994). Recent findings, however, have shown that the object-based cueing effect is influenced by object orientation, suggesting that the cueing effect might be due to a more general facilitation of attentional shifts across the horizontal meridian (Al-Janabi & Greenberg, Attention, Perception, & Psychophysics, 1-17, 2016; Pilz, Roggeveen, Creighton, Bennet, & Sekuler, PLOS ONE, 7, e30693, 2012). The aim of this study was to investigate whether the object-based cueing effect is influenced by object similarity and orientation. According to the object-based attention account, objects that are less similar to each other should elicit stronger object-based cueing effects independent of object orientation, whereas the horizontal meridian theory would not predict any effect of object similarity. We manipulated object similarity by using a color (Exp. 1, Exp. 2A) or shape change (Exp. 2B) to distinguish two rectangles in a variation of the classic two-rectangle paradigm (Egly et al., 1994). We found that the object-based cueing effects were influenced by the orientation of the rectangles and strengthened by object dissimilarity. We suggest that object-based cueing effects are strongly affected by the facilitation of attention along the horizontal meridian, but that they also have an object-based attentional component, which is revealed when the dissimilarity between the presented objects is accentuated.

Toward the influence of temporal attention on the selection of targets in a visual search task: An ERP study.

We used ERPs to investigate whether temporal attention interacts with spatial attention and feature-based attention to enhance visual processing. We presented a visual search display containing one singleton stimulus among a set of homogenous distractors. Participants were asked to respond only to target singletons of a particular color and shape that were presented in an attended spatial position. We manipulated temporal attention by presenting a warning signal before each search display and varying the foreperiod (FP) between the warning signal and the search display in a blocked manner. We observed distinctive ERP effects of both spatial and temporal attention. The amplitudes for the N2pc, SPCN, and P3 were enhanced by spatial attention indicating a processing benefit of relevant stimulus features at the attended side. Temporal attention accelerated stimulus processing; this was indexed by an earlier onset of the N2pc component and a reduction in reaction times to targets. Most importantly, temporal attention did not interact with spatial attention or stimulus features to influence visual processing. Taken together, the results suggest that temporal attention fosters visual perceptual processing in a visual search task independently from spatial attention and feature-based attention; this provides support for the nonspecific enhancement hypothesis of temporal attention.

Context-dependent impact of presuppositions on early magnetic brain responses during speech perception.

Discourse structure enables us to generate expectations based upon linguistic material that has already been introduced. The present magnetoencephalography (MEG) study addresses auditory perception of test sentences in which discourse coherence was manipulated by using presuppositions (PSP) that either correspond or fail to correspond to items in preceding context sentences with respect to uniqueness and existence. Context violations yielded delayed auditory M50 and enhanced auditory M200 cross-correlation responses to syllable onsets within an analysis window of 1.5s following the PSP trigger words. Furthermore, discourse incoherence yielded suppression of spectral power within an expanded alpha band ranging from 6 to 16Hz. This effect showed a bimodal temporal distribution, being significant in an early time window of 0.0-0.5s following the PSP trigger and a late interval of 2.0-2.5s. These findings indicate anticipatory top-down mechanisms interacting with various aspects of bottom-up processing during speech perception.

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.

Does temporal preparation speed up visual processing? Evidence from the N2pc.

A growing number of studies show that temporal preparation, which denotes processes of anticipation and preparation for an upcoming stimulus, facilitates perceptual processing. Recently, it has been hypothesized that this perceptual benefit arises due to an acceleration of early perceptual processing. Whereas this idea receives some direct support from a recent study showing that temporal preparation reduces the latency of early auditory ERPs, supportive evidence regarding the visual modality lacks so far. To further investigate this acceleration account, we measured the latency of early visual ERPs in a visual search task. We observed that temporal preparation, manipulated via constant foreperiods, reduced the latency of early visual ERPs, specifically the N2pc as an index of attentional target processing. This finding supports a modality-independent acceleration of perceptual processing by temporal preparation.

Overt head movements moderate the effect of depressive symptoms on mood regulation.

A dysfunction in the regulation of negative mood states is one of the core symptoms of depression. Research has found that levels of depression are associated with the intensity of the mood-regulation deficit. The present study aimed to explore the role the body plays in mood-regulation processes. More specifically, we studied whether head movements can influence mood persistence in dysphoric states. Subsequent to a sad-mood induction, participants were presented with a set of positive pictures immediately after performing either vertical (i.e., nodding) or lateral (i.e., shaking) head movements. We considered changes in mood from before to after the experimental task as an index of the effectiveness of mood regulation. As expected, the results showed that higher initial levels of depressive symptoms were associated with greater persistence of sad mood. More importantly, this association was present in participants who shook their heads, but not in those who nodded. These results show that body movements can contribute to mood-regulation processes, thus expanding our knowledge of the psychopathology of mood disorders.

Priming the mental time-line: effects of modality and processing mode.

The notion of a mental time-line (i.e., past corresponds to left and future corresponds to right) supports the conceptual metaphor view assuming that abstract concepts like "time" are grounded in cognitively more accessible concepts like "space." In five experiments, we further investigated the relationship between temporal and spatial representations and examined whether or not the spatial correspondents of time are unintentionally activated. We employed a priming paradigm, in which visual or auditory prime words (i.e., temporal adverbs such as yesterday, tomorrow) preceded a colored square. In all experiments, participants discriminated the color of this square by responding with the left or the right hand. Although the temporal reference of the priming adverb was task irrelevant in Experiment 1, visually presented primes facilitated responses to the square in correspondence with the direction of the mental time-line. This priming effect was absent in Experiments 2, 3, and 5, in which the primes were presented auditorily and the temporal reference of the words could be ignored. The effect, however, emerged when attention was oriented to the temporal content of the auditory prime words in Experiment 4. The results suggest that task demands differentially modulate the activation of the mental time-line within the visual and auditory modality and support a flexible association between conceptual codes.

Effects of sleep loss and circadian rhythm on executive inhibitory control in the Stroop and Simon tasks.

This study assessed the influence of sleep loss and circadian rhythm on executive inhibitory control (i.e., the ability to inhibit conflicting response tendencies due to irrelevant information). Twelve ordinarily diurnally active, healthy young male participants performed the Stroop and the Simon task every 3 h in a 40-h constant routine protocol that comprised constant wakefulness under controlled behavioral and environmental conditions. In both tasks, overall performance showed clear circadian rhythm and sleep-loss effects. However, both Stroop and Simon interference remained unchanged across the 40 h of wakefulness, suggesting that neither cumulative sleep loss nor the circadian clock affects executive inhibitory control. The present findings challenge the widely held view that executive functions are especially vulnerable to the influence of sleep loss and circadian rhythm.

Processing two tasks with varying task order: central stage duration influences central processing order.

In a recent study, Sigman and Dehaene (2006, PLoS Biology, 4, 1227-1238) reported that perceptual processing duration influences processing order of two tasks in the psychological refractory period paradigm (PRP). The present study examines whether the duration of central processes also influences processing order. For this purpose, we employed letter tasks with different central processing durations and varied task order in the PRP. In one part of the experiment, a tone discrimination task was combined with a similar time-consuming letter discrimination task. In the other part, the tone task was combined with a more time-consuming letter task, which required a mental rotation of the letter thereby prolonging central processing. If the duration of central processes influences processing order, participants should perform the tone task first more often when it is presented with the more time-consuming mental rotation task, than when it is presented with the similar time-consuming letter task. The results clearly confirm this prediction and thus show that not only perceptual processing duration but also central processing duration affects processing order in a dual-task situation. We suggest that the reported effect mirrors a tendency of participants to minimize total reaction time to both tasks by reducing slack time.

Does temporal preparation increase the rate of sensory information accumulation?

Recent studies showed that temporal preparation, i.e., the ability to prepare for an upcoming stimulus, improves perceptual processing. The mechanisms underlying this benefit are still controversial. Based upon the theoretical framework of accumulation models, it has been proposed that the accumulation of sensory stimulus information begins earlier when participants are temporally prepared than when they are unprepared. Alternatively, however, temporal preparation might also affect the accumulation rate of sensory information. In the present study, we examined these possibilities. Specifically, in three experiments, we manipulated participants' decision criterion. This manipulation should interact with any experimental manipulation affecting the rate of information processing, but produce additive effects with any manipulation affecting the onset of information accumulation rather than its rate. We obtained additive effects on RT, irrespective of whether the decision criterion was manipulated by increasing catch trial proportion or nogo trial proportion. These results suggest that temporal preparation improves perceptual processing by operating on the onset of sensory information accumulation rather than the rate of sensory information accumulation.