Frontal and parietal EEG asymmetries interact to predict attentional bias to threat

Frontal and parietal electroencephalographic (EEG) asymmetries mark vulnerability to depression and anxiety. Drawing on cognitive theories of vulnerability, we hypothesise that cortical asymmetries predict attention to threat. Participants completed a dot-probe task in which bilateral face displays were followed by lateralised targets at either short (300 ms) or long (1050 ms) SOA. We also measured N2pc to face onset as an index of early attentional capture. At long SOA only, frontal and parietal asymmetry interacted to predict attentional bias to angry faces. Those with leftward frontal asymmetry showed no attentional bias. Among those with rightward frontal asymmetry those with low right parietal activity showed vigilance for threat, and those with high right parietal activity showed avoidance. Asymmetry was not related to the N2pc or to attentional bias at the short SOA. Findings suggest that trait asymmetries reflect function in a fronto-parietal network that controls attention to threat.     

When hearing the bark helps to identify the dog: Semantically-congruent sounds modulate the identification of masked pictures

We report a series of experiments designed to assess the effect of audiovisual semantic congruency on the identification of visually-presented pictures. Participants made unspeeded identification responses concerning a series of briefly-presented, and then rapidly-masked, pictures. A naturalistic sound was sometimes presented together with the picture at a stimulus onset asynchrony (SOA) that varied between 0 and 533 ms (auditory lagging). The sound could be semantically congruent, semantically incongruent, or else neutral (white noise) with respect to the target picture. The results showed that when the onset of the picture and sound occurred simultaneously, a semantically-congruent sound improved, whereas a semantically-incongruent sound impaired, participants’ picture identification performance, as compared to performance in the white-noise control condition. A significant facilitatory effect was also observed at SOAs of around 300 ms, whereas no such semantic congruency effects were observed at the longest interval (533 ms). These results therefore suggest that the neural representations associated with visual and auditory stimuli can interact in a shared semantic system. Furthermore, this crossmodal semantic interaction is not constrained by the need for the strict temporal coincidence of the constituent auditory and visual stimuli. We therefore suggest that audiovisual semantic interactions likely occur in a short-term buffer which rapidly accesses, and temporarily retains, the semantic representations of multisensory stimuli in order to form a coherent multisensory object representation. These results are explained in terms of Potter’s (1993) notion of conceptual short-term memory.     

Masked emotional priming: A double dissociation between direct and indirect effects reveals non-conscious processing of emotional information beyond valence

We demonstrate non-conscious processing beyond valence by employing the masked emotional priming paradigm (Rohr, Degner, & Wentura, 2012) with a stimulus-onset asynchrony (SOA) variation. Emotional faces were briefly presented and directly masked, followed by the target face, using a SOA of either 43 ms or 143 ms. Targets were categorized as happy, angry, fearful, or sad. With short SOA, we replicated the differentiated priming effect within the negative domain (i.e., angry differentiate from fearful/sad). A direct test of prime awareness indicated that primes could not be discriminated consciously in this condition. With long SOA, however, we did not observe the priming effect whereas the direct test indicated some degree of conscious processing. Thus, indirect effects dissociated from direct effects in our study, an indication for non-conscious processing. Thereby, the present study provides evidence for non-conscious processing of emotional information beyond a simple positive-negative differentiation.     

Body image concern and selective attention to disgusting and non-self appearance-related stimuli

Although selective attention to one's own appearance has been widely documented in studies of body dysmorphic disorder (BDD), little is known about attentional bias toward non-self appearance-related stimuli in BDD. Furthermore, despite reports of heightened experience of disgust in BDD, it is unknown whether these individuals differentially attend to disgusting stimuli and whether disgust is important in processing of unattractive stimuli. We used a dot probe procedure to investigate the relationship between dysmorphic concern, a defining feature of BDD, and selective attention to faces, attractive, unattractive and disgusting images in a female heterosexual student population (N = 92). At the long stimulus presentation (1000 ms), dysmorphic concern was positively associated with attention to faces in general and attractive appearance-related images. In contrast, at the short stimulus presentation (200 ms), there was a positive association between dysmorphic concern and disgusting images. Implications for theoretical models of BDD are discussed.     

Global shape integration and illusory form perception in the absence of awareness

Previous research on perceptual organization operations still provides contradictory evidence on whether the integration of sparse local elements into coherently unified shapes and the construction of the illusory form are accomplished without the need of awareness. In the present study, three experiments were conducted in which participants were presented with masked (Experiment 1, SOA = 27 ms; Experiment 2; SOA = 53 ms) and unmasked (Experiment 3) primes consisting of geometric shapes (a square or a diamond) that could be congruent or incongruent with subsequent probe stimuli (square vs. diamond). Furthermore, the primes were divided into: a grouping condition (where local elements may group together into global shapes), an illusory condition (where the arrangement of local elements produced illusory shapes) and a hybrid condition (where both operations were presented simultaneously). While no priming effects were found for the shortest SOA (27 ms), both grouping and illusory primes produced significant priming effects in the longer SOA (53 ms). On the other hand, results in Experiment 3 (unmasked) showed strong priming effects for the grouping of the inducers in both the grouping and the hybrid conditions, and also a significant but weaker priming effect for the illusory condition. Overall, our results support the possibility of the integration of local visual features into a global shape in the absence of awareness and, likewise, they suggest an early –subliminal– construction of the illusory shape, implying that feedback projections from higher to lower visual areas are not crucial in the construction of the illusory form.     

Immediate truth – Temporal contiguity between a cognitive problem and its solution determines experienced veracity of the solution

A temporal contiguity hypothesis for the experience of veracity is tested which states that a solution candidate to a cognitive problem is more likely to be experienced as correct the faster it succeeds the problem. Experiment 1 varied the onset time of the appearance of proposed solutions to anagrams (50 ms vs. 150 ms) and found for both correct and incorrect candidates that faster appearing solutions were more frequently judged as being correct, although participants were not aware of the difference in onset delay. Experiment 2 replicated this effect with mathematical equations, shorter onset latencies (0 ms vs. 50 ms), and a reversed sequence (presenting first the solution and then the problem). Experiment 3 showed that the probability of judging a word as the solution of a remote associate insight problem decreases linearly with increasing onset delay (50 ms, 150 ms, 300 ms). Possible neurobiological-cognitive explanations for this effect are proposed.     

Very brief exposure: The effects of unreportable stimuli on fearful behavior

A series of experiments tested the hypothesis that very brief exposure to feared stimuli can have positive effects on avoidance of the corresponding feared object. Participants identified themselves as fearful of spiders through a widely used questionnaire. A preliminary experiment showed that they were unable to identify the stimuli used in the main experiments. Experiment 2 (N = 65) compared the effects of exposure to masked feared stimuli at short and long stimulus onset asynchronies (SOA). Participants were individually administered one of three continuous series of backwards masked or non-masked stimuli: unreportable images of spiders (25-ms SOA), clearly visible images of spiders (500-ms SOA), or unreportable images of trees (25-ms SOA). Immediately thereafter, they engaged in a Behavioral Avoidance Test (BAT) with a live, caged tarantula. Exposure to unreportable images of spiders resulted in greater approach towards the tarantula than unreportable neutral images. A post-hoc comparison with clearly visible exposure to these same images approached significance. These effects were maintained at a 1-week follow-up (N = 57). In Experiment 3 (N = 26), participants engaged in the BAT 1 week prior to the exposure manipulation in order to provide a baseline measurement of their avoidant behavior, and again immediately after the exposure manipulation. Exposure to unreportable images of spiders reduced avoidance of the tarantula. Similar exposure to trees did not. Implications for the non-conscious basis of fear are discussed.     

Unconscious task set priming with phonological and semantic tasks

Whether unconscious stimuli can modulate the preparation of a cognitive task is still controversial. Using a backward masking paradigm, we investigated whether the modulation could be observed even if the prime was made unconscious in 100% of the trials. In two behavioral experiments, subjects were instructed to initiate a phonological or semantic task on an upcoming word, following an explicit instruction and an unconscious prime. When the SOA between prime and instruction was sufficiently long (84 ms), primes congruent with the task set instruction led to speedier responses than incongruent primes. In the other condition (36 ms), no task set priming was observed. Repetition priming had the opposite tendency, suggesting the observed task set facilitation cannot be ascribed solely to perceptual repetition priming. Our results therefore confirm that unconscious information can modulate cognitive control for currently active task sets, providing sufficient time is available before the conscious decision.     

ERP signatures of conscious and unconscious word and letter perception in an inattentional blindness paradigm

A three-phase inattentional blindness paradigm was combined with ERPs. While participants performed a distracter task, line segments in the background formed words or consonant-strings. Nearly half of the participants failed to notice these word-forms and were deemed inattentionally blind. All participants noticed the word-forms in phase 2 of the experiment while they performed the same distracter task. In the final phase, participants performed a task on the word-forms. In all phases, including during inattentional blindness, word-forms elicited distinct ERPs during early latencies (∼200–280 ms) suggesting unconscious orthographic processing. A subsequent ERP (∼320–380 ms) similar to the visual awareness negativity appeared only when subjects were aware of the word-forms, regardless of the task. Finally, word-forms elicited a P3b (∼400–550 ms) only when these stimuli were task-relevant. These results are consistent with previous inattentional blindness studies and help distinguish brain activity associated with pre- and post-perceptual processing from correlates of conscious perception.     

Rescuing stimuli from invisibility: Inducing a momentary release from visual masking with pre-target entrainment

At near-threshold levels of stimulation, identical stimulus parameters can result in very different phenomenal experiences. Can we manipulate which stimuli reach consciousness? Here we show that consciousness of otherwise masked stimuli can be experimentally induced by sensory entrainment. We preceded a backward-masked stimulus with a series of rapid visual events presented at 12 Hz for 800 ms. Peaks in visual sensitivity (d′) were observed when the target appeared at the time that the next entraining stimuli would have occurred. Observers’ sensitivity for identical masked near-threshold stimuli increased by factors as large as 55%, but only at this precise moment in time. These data thus reveal that awareness of near-threshold stimuli can be manipulated by entrainment to rhythmic events, supporting the functional role of induced oscillations in underlying cortical excitability, and suggest a plausible mechanism of temporal attention.     

Highly correlated stimuli do not necessarily facilitate the measurement of unconscious perception: Exclusion failure is hard to find in forced-choice tasks

Persaud and McLeod (2008) report that unconscious perception is easier to measure with forced-choice exclusion tasks when the stimuli are highly similar, such as choosing between the letters ‘h’ and ‘b’. The high degree of stimulus similarity may decrease conscious awareness of the target stimuli while leaving unconscious cognition intact. The present experiments used forced-choice exclusion tasks (i.e., choosing the opposite of a masked target stimulus) with the aim of replicating these findings. No evidence of relevant perception – either conscious or unconscious – was obtained with short duration targets. The forced-choice exclusion task was correctly performed at longer target durations (25 ms and higher), which suggests conscious perception of the target stimuli. We conclude that increasing stimulus similarity does not reliably produce exclusion failure effects and does not appear to facilitate the measurement of unconscious cognition.     

Binocular vision enhances a rapidly evolving affordance priming effect: Behavioural and TMS evidence

Extensive research has suggested that simply viewing an object can automatically prime compatible actions for object manipulation, known as affordances. Here we explored the generation of covert motor plans afforded by real objects with precision (‘pinchable’) or whole-hand/power (‘graspable’) grip significance under different types of vision. In Experiment 1, participants viewed real object primes either monocularly or binocularly and responded to orthogonal auditory stimuli by making precision or power grips. Pinchable primes facilitated congruent precision grip responses relative to incongruent power grips, and vice versa for graspable primes, but only in the binocular vision condition. To examine the temporal evolution of the binocular affordance effect, participants in Experiment 2 always viewed the objects binocularly but made no responses, instead receiving a transcranial magnetic stimulation pulse over their primary motor cortex at three different times (150, 300, 450 ms) after prime onset. Motor evoked potentials (MEPs) recorded from a pinching muscle were selectively increased when subjects were primed with a pinchable object, whereas MEPs from a muscle associated with power grips were increased when viewing graspable stimuli. This interaction was obtained both 300 and 450 ms (but not 150 ms) after the visual onset of the prime, characterising for the first time the rapid development of binocular grip-specific affordances predicted by functional accounts of the affordance effect.     

Event-related potentials as brain correlates of item specific proportion congruent effects

The item-specific proportion congruency (ISPC) effect is consistent with the idea that control processes can be applied rapidly in accord with previously experienced conflict for a particular category. An alternative account of this effect is that it reflects item-specific learning processes unrelated to control at the level of the category. The accounts predict the same behaviour but differ in terms of electrophysiological predictions. Two experiments examined the ISPC effect with a particular focus on neural correlates that might reveal whether, and how early in processing, high and low proportion congruent items are treated as distinct classes of stimuli. For both tasks, the proportion congruency category was distinguished prior to the congruence of the specific stimulus, as early as 100 ms post-stimulus onset for the global/local identification task (Experiment 1) and 150 ms for the Stroop task (Experiment 2). The results support an on-line control account of ISPC effects.     

Distortions of temporal integration and perceived order caused by the interplay between stimulus contrast and duration

Stimulus contrast and duration effects on visual temporal integration and order judgment were examined in a unified paradigm. Stimulus onset asynchrony was governed by the duration of the first stimulus in Experiment 1, and by the interstimulus interval in Experiment 2. In Experiment 1, integration and order uncertainty increased when a low contrast stimulus followed a high contrast stimulus, but only when the second stimulus was 20 or 30 ms. At 10 ms duration of the second stimulus, integration and uncertainty decreased. Temporal order judgments at all durations of the second stimulus were better for a low contrast stimulus following a high contrast one. By contrast, in Experiment 2, a low contrast stimulus following a high contrast stimulus consistently produced higher integration rates, order uncertainty, and lower order accuracy. Contrast and duration thus interacted, breaking correspondence between integration and order perception. The results are interpreted in a tentative conceptual framework.     

Ignition’s glow: Ultra-fast spread of global cortical activity accompanying local “ignitions” in visual cortex during conscious visual perception

Despite extensive research, the spatiotemporal span of neuronal activations associated with the emergence of a conscious percept is still debated. The debate can be formulated in the context of local vs. global models, emphasizing local activity in visual cortex vs. a global fronto-parietal “workspace” as the key mechanisms of conscious visual perception. These alternative models lead to differential predictions with regard to the precise magnitude, timing and anatomical spread of neuronal activity during conscious perception. Here we aimed to test a specific aspect of these predictions in which local and global models appear to differ – namely the extent to which fronto-parietal regions modulate their activity during task performance under similar perceptual states. So far the main experimental results relevant to this debate have been obtained from non-invasive methods and led to conflicting interpretations. Here we examined these alternative predictions through large-scale intracranial measurements (Electrocorticogram – ECoG) in 43 patients and 4445 recording sites. Both ERP and broadband high frequency (50–150 Hz – BHF) responses were examined through the entire cortex during a simple 1-back visual recognition memory task. Our results reveal short latency intense visual responses, localized first in early visual cortex followed (at ∼200 ms) by higher order visual areas, but failed to show significant delayed (300 ms) visual activations. By contrast, oddball image repeat events, linked to overt motor responses, were associated with a significant increase in a delayed (300 ms) peak of BHF power in fronto-parietal cortex. Comparing BHF responses with ERP revealed an additional peak in the ERP response – having a similar latency to the well-studied P3 scalp EEG response. Posterior and temporal regions demonstrated robust visual category selectivity. An unexpected observation was that high-order visual cortex responses were essentially concurrent (at ∼200 ms) with an ultra-fast spread of signals of lower magnitude that invaded selected sites throughout fronto-parietal cortical areas. Our results are compatible with local models in demonstrating a clear task-dependence of the 300 ms fronto-parietal activation. However, they also reveal a more global component of low-magnitude and poor content selectivity that rapidly spreads into fronto-parietal sites. The precise functional role of this global “glow” remains to be elucidated.     

Evaluating feedback time delay during perturbed and unperturbed balance in handstand

Feedback delays in balance are often assessed using muscle activity onset latencies in response to discrete perturbations. The purpose of the study was to calculate EMG latencies in perturbed handstand, and determine if delays are different to unperturbed handstand. Twelve national level gymnasts completed 12 perturbed and 10 unperturbed (five eyes open and five closed) handstands. Forearm EMG latencies during perturbed handstands were assessed against delay estimates calculated via: cross correlations of wrist torque and COM displacement, a proportional and derivative model of wrist torque and COM displacement and velocity (PD model), and a PD model incorporating a passive stiffness component (PS-PD model). Delays from the PD model (161 ± 14 ms) and PS-PD model (188 ± 14 ms) were in agreement with EMG latencies (165 ± 14 ms). Cross correlations of COM displacement and wrist torque provided unrealistically low estimates (5 ± 9 ms). Delays were significantly lower during perturbed (188 ± 14 ms) compared to unperturbed handstand (eyes open: 207 ± 12 ms; eyes closed: 220 ± 19 ms). Significant differences in delays and model parameters between perturbed and unperturbed handstand support the view that balance measures in perturbed testing should not be generalised to unperturbed balance.     

Attentional and interpretative biases in appearance concern: An investigation of biases in appearance-related information processing

The present study examined associations between high levels of appearance concern and information processing biases in interpretation and attention. An opportunity sample (N = 79) categorised ambiguous stimuli as related or unrelated to appearance. Participants then responded to the same stimuli in a modified visual dot-probe task assessing attentional bias. Participant responses were assessed in relation to level of appearance concern. The results indicated a valence specific bias towards interpretation of ambiguous stimuli as negative and appearance-related in individuals with higher levels of concern. There was also evidence of attentional bias towards information perceived as appearance-related in participants with higher levels of appearance concern. The study findings suggest that association between appearance-orientated information processing biases and level of appearance concern; this association may lead to mutually reinforcing bias and concern.     

The relationship between visual attention and expertise in sports

ObjectivesGiven the prevalence of misperception and failed perception, particularly in attention-demanding team sports, surprisingly few studies have explored whether experts in team sports differ from other athletes and from non-athletes in their basic attention abilities.MethodIn this study, we examined group differences between experts in team handball (n = 40), athletes from non-team sports (n = 40), and novice athletes (n = 40) using a battery of three attention tasks: a functional field of view task, a multiple-object tracking task, and an inattentional blindness task.ResultsPerformance on the three attention tasks was largely independent, with no significant correlations among the tasks. Team sports experts showed no better performance on the basic attention tasks than did athletes from non-teams sports or novice athletes.ConclusionsThe finding that all basic attention tasks are largely independent provides preliminary support for the idea that attentional breadth, tracking performance, and inattentional blindness are distinct attentional processes. Our results demonstrate that sports expertise effects are unrelated to basic differences in attention—expertise does not appear to produce differences in basic attention and basic differences in attention do not appear to predict eventual expertise. Further experiments could focus on the ways in which more specific attentional strategies and processes contribute to sports performance.     

Distributed attentional deficits in chronic methamphetamine abusers: Evidence from the Attentional Network Task (ANT)

ObjectiveThe goal of the present study was to examine distributed attentional functions in long-term but currently abstinent methamphetamine (MA) abusers using a task that measures attentional alertness, orienting, and conflict resolution.MethodsThirty currently abstinent MA abusers (1 month–5 years) and 22 healthy non-substance using adults were administered a multimodal version of the Attentional Network Task (ANT-I). In this task subjects identified the direction of a centrally presented arrow using a key press. Analyses examined the interaction between alerting tones, location cueing and congruency between the target arrows and flanking distractor stimuli.ResultsAll participants were faster when an auditory tone preceded the trial onset (p < 0.001), on trials in which a valid cue preceded the location of the target arrow (p < 0.001), and on congruent trials (i.e., when all display arrows faced in the same direction) (p < 0.001). Of primary interest was the finding that MA abusers were more influenced by the conflict between the peripheral arrows and the central target arrow (p = 0.009). There were also correlations between length of drug sobriety and executive function as well as between drug-induced psychiatric symptoms and alertness.ConclusionsThese results suggest that chronic MA abusers display cognitive deficits that may reflect a specific vulnerability to distraction on a task of executive function. These findings are consistent with other studies that have reported deficits in anterior attentional systems and top-down cognitive control.     

Multisensory integration in children with Developmental Coordination Disorder

This study examines how multisensory stimuli affect the performance of children with Developmental Coordination Disorder (DCD) on a choice reaction time (CRT) task. Ten children with DCD, identified using the Movement Assessment Battery for Children-2, aged 7–10 years (4F, M = 8 y 3 m, SD = 17 m) and 10 typically developing peers (TDC) (5F, M = 8 y 4 m, SD = 17 m) reached to unimodal (auditory (AO), visual (VO)) and bimodal (audiovisual (AV)) stimuli at one of three target locations. A multisensory (AV) stimulus reduced RTs for both groups (p < 0.001, η² = 0.36). While the children with DCD had a longer RT in all conditions, the AV stimulus produced RTs in children with DCD (494 ms) that were equivalent to those produced by the TDC to the VO stimulus (493 ms). Movement Time (DCD = 486 ms; TDC = 434 ms) and Path Length (DCD = 25.6 cm; TDC = 24.2 cm) were longer in children with DCD compared to TDC as expected (p < 0.05). Only the TDC benefited from the AV information for movement control, as deceleration time of the dominant hand was seen to decrease when moving to an AV stimulus (p < 0.05). Overall, data shows children with DCD do benefit from a bimodal stimulus to plan their movement, but do not for movement control. Further research is required to understand if this is a result of impaired multisensory integration.