Distractor Trials Research Articles

Lying relies on the truth

Cognitive models of deception focus on the conflict-inducing nature of the truth activation during lying. Here we tested the counterintuitive hypothesis that the truth can also serve a functional role in the act of lying. More specifically, we examined whether the construction of a lie can involve a two-step process, where the first step entails activating the truth, based upon which a lie response can be formulated in a second step. To investigate this hypothesis, we tried to capture the covert truth activation in a reaction-time based deception paradigm. Together with each question, we presented either the truth or lie response as distractors. If lying depends on the covert activation of the truth, deceptive responses would thus be facilitated by truth distractors relative to lie distractors. Our results indeed revealed such a “covert congruency” effect, both in errors and reaction times (Experiment 1). Moreover, stimulating participants to use the distractor information by increasing the proportion of truth distractor trials enlarged the “covert congruency” effects, and as such confirmed that the effects operate at a covert response level (Experiment 2). Our findings lend support to the idea that lying relies on a first step of truth telling, and call for a shift in theoretical thinking that highlights both the functional and interfering properties of the truth activation in the lying process.

Crossmodal congruency effects based on stimulus identity

We investigated whether the crossmodal congruency effect, normally observed in spatial compatibility tasks, would also affect performance on a task based on discriminating stimulus identity (i.e., a non-spatial dimension). Two rhythms were presented to participants' eyes, ears, and/or hands in a 4-alternative rhythm discrimination task. Stimulus identity and stimulus modality were varied orthogonally. When the target and distractor rhythms were presented in different sensory modalities, significant crossmodal congruency effects were observed in all conditions (i.e., performance on the incongruent distractor trials was significantly more error-prone than on the congruent distractor trials). In contrast to the results of previous studies, these crossmodal distractor effects were neither based on the spatial compatibility of the stimuli nor on an abstract semantic matching of stimulus identity, but instead on the identity of the target rhythm. Intriguingly, the magnitude of the crossmodal congruency effects differed as a function of the target modality, but were unaffected by the modality of the distractor.

The role of working memory in auditory selective attention

A growing body of research now demonstrates that working memory plays an important role in controlling the extent to which irrelevant visual distractors are processed during visual selective attention tasks (e.g., Lavie, Hirst, De Fockert, & Viding, 2004). Recently, it has been shown that the successful selection of tactile information also depends on the availability of working memory (Dalton, Lavie, & Spence, 2009). Here, we investigate whether working memory plays a role in auditory selective attention. Participants focused their attention on short continuous bursts of white noise (targets) while attempting to ignore pulsed bursts of noise (distractors). Distractor interference in this auditory task, as measured in terms of the difference in performance between congruent and incongruent distractor trials, increased significantly under high (vs. low) load in a concurrent working-memory task. These results provide the first evidence demonstrating a causal role for working memory in reducing interference by irrelevant auditory distractors.

Neural Correlates of Impaired Cognitive-Behavioral Flexibility in Anorexia Nervosa

Impaired cognitive-behavioral flexibility is regarded as a trait marker in anorexia nervosa patients. The authors sought to investigate the neural correlates of this deficit in executive functioning in anorexia nervosa. Fifteen women with anorexia nervosa and 15 age-matched healthy comparison women underwent event-related functional MRI while performing a target-detection task. The task distinguished between shifts in behavioral response and shifts in cognitive set. It involved infrequent target and non-target distractor stimuli embedded in a sequence of prepotent standard stimuli. Relative to comparison subjects, anorexia nervosa patients showed a significantly higher error rate in behavioral response shifting, independent of whether those runs also involved cognitive set shifting. During behavioral response shifting, patients showed reduced activation in the left and right thalamus, ventral striatum, anterior cingulate cortex, sensorimotor brain regions, and cerebellum that differed significantly from the comparison group but showed dominant activation in frontal and parietal brain regions. These differential activations in patients and comparison subjects were specific to shifts in behavioral response: except for thalamic activation, they were not observed in response to non-target distractor trials that required no alteration in behavioral response. Impaired behavioral response shifting in anorexia nervosa seems to be associated with hypoactivation in the ventral anterior cingulate-striato-thalamic loop that is involved in motivation-related behavior. In contrast, anorexia nervosa patients showed predominant activation of frontoparietal networks that is indicative of effortful and supervisory cognitive control during task performance.

Visual working memory and delay activity in highly selective neurons in the inferior temporal cortex

Visual working memory and delay activity in highly selective neurons in the inferior temporal cortex

Development of Visual Selection in 3‐ to 9‐Month‐Olds: Evidence From Saccades to Previously Ignored Locations

We examined changes in the efficiency of visual selection over the first postnatal year with an adapted version of a spatial negative priming paradigm. In this task, when a previously ignored location becomes the target to be selected, responses to it are impaired, providing a measure of visual selection. Oculomotor latencies to target selection were the dependent measure. Each trial consisted of a prime and a probe presentation, separated by a 67-, 200-, or 550-msec interstimulus interval (ISI), to test the efficiency of selection as a function of processing time. In the prime, the target was accompanied by a distractor item. In the probe, the target appeared either in the location formerly occupied by the distractor (repeated distractor trials) or in one of the other two locations (control trials). We tested 41 infants in each of 3 age groups (3, 6, and 9 months) on the three different ISIs. Nine-month-old infants' saccade latencies were slowed on repeated distractors relative to control trials, given sufficiently long ISIs. Saccade latencies in the youngest two age groups showed only facilitation on repeated distractor trials at short ISIs. These results suggest that visual selection efficiency is a function of the interaction of the processing limitations of a system with environmental conditions, in this case the time allotted for the selection process.

Electrophysiological correlates of crossmodal visual distractor congruency effects: Evidence for response conflict

To investigate the basis of crossmodal visual distractor congruency effects, we recorded event-related brain potentials (ERP) while participants performed a tactile location-discrimination task. Participants made speeded tactile location-discrimination responses to tactile targets presented to the index fingers or thumbs while ignoring simultaneously presented task-irrelevant visual distractor stimuli at either the same (congruent) or a different (incongruent) location. Behavioural results were in line with previous studies, showing slowed response times and increased error rates on incongruent compared with congruent visual distractor trials. To clarify the effect of visual distractors on tactile processing, concurrently recorded ERPs were analyzed for poststimulus, preresponse, and postresponse modulations. An enhanced negativity was found in the time range of the N2 component on incongruent compared with congruent visual distractor trials prior to correct responses. In addition, postresponse ERPs showed the presence of error-related negativity components on incorrect-response trials and enhanced negativity for congruent-incorrect compared with incongruent-incorrect trials. This pattern of ERP results has previously been related to response conflict (Yeung, Botvinick, & Cohen, 2004). Importantly, no modulation of early somatosensory ERPs was present prior to the N2 time range, which may have suggested the contribution of other perceptual or postperceptual processes to crossmodal congruency effects. Taken together, our results suggest that crossmodal visual distractor effects are largely due to response conflict.

Scary voices & applauding hands: Rapid and opposing effects of emotional valence revealed by AEPs

Event Abstract Back to Event Scary voices & applauding hands: Rapid and opposing effects of emotional valence revealed by AEPs Melanie Aeschlimann1*, J. F. Knebel1, L. Spierer1, S. Clarke1 and Micah M. Murray1, 2, 3 1 Centre Hospitalier Universitaire Vaudois and University of Lausanne, Switzerland 2 Centre Hospitalier Universitaire Vaudois and University of Lausanne, Radiology service, Switzerland 3 Center for Biomedical Imaging of Lausanne and Geneva, EEG Brain Mapping Core, Switzerland The emotional information conveyed by sounds is immediately evident upon watching a muted film. However, the neurophysiological mechanisms mediating the emotional processing of sounds remain unresolved. Existing auditory evoked potential (AEP) studies of humans were limited to comparisons between neutral and negative emotions as well as to environmental sounds, excluding non-verbal vocalizations. However, recent psychophysical results have demonstrated that human vocalizations (HV) are a distinct emotional category of environmental sounds (Aeschlimann et al. 2008 Brain Topogr 20:239-48). The present AEP study investigated the spatio-temporal dynamics mediating the emotional processing of two categories of environmental sounds (HV and non-vocalizations; NV) varying in their emotional valences (positive, negative, and neutral). The stimulus battery was controlled in its duration, RMS intensity, spectrogram, and recognition confidence. 16 participants (8 men; 8 women) completed an oddball detection task with sound category. The target category was counterbalanced across blocks of trials and was presented on 1/12th of trials. Electrical neuroimaging analyses of the AEPs were based on distractor trials only. Analyses of the global field power (millisecond-by-millisecond ANOVA) revealed an interaction between factors of category and emotional valence beginning at ~40ms post-stimulus onset (i.e. during the P50 component). Post-hoc ANOVAs with each category, separately, also revealed main effects of valence at this latency. In the case of HV, this followed from a significantly stronger P50 response to negative emotions. By contrast, in the case of NV, this followed from a stronger P50 response to positive emotions. These results suggest that emotional valence may be differentially processed according to the category of the sound source during the initial states of auditory information processing. We discuss these results in terms of a spatio-temporal model of auditory object recognition. Conference: 10th International Conference on Cognitive Neuroscience, Bodrum, Turkey, 1 Sep - 5 Sep, 2008. Presentation Type: Poster Presentation Topic: Emotional Processing Citation: Aeschlimann M, Knebel JF, Spierer L, Clarke S and Murray MM (2008). Scary voices & applauding hands: Rapid and opposing effects of emotional valence revealed by AEPs. Conference Abstract: 10th International Conference on Cognitive Neuroscience. doi: 10.3389/conf.neuro.09.2009.01.204 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 08 Dec 2008; Published Online: 08 Dec 2008. * Correspondence: Melanie Aeschlimann, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, Melanie.Aeschlimann@chuv.ch Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Melanie Aeschlimann J. F Knebel L. Spierer S. Clarke Micah M Murray Google Melanie Aeschlimann J. F Knebel L. Spierer S. Clarke Micah M Murray Google Scholar Melanie Aeschlimann J. F Knebel L. Spierer S. Clarke Micah M Murray PubMed Melanie Aeschlimann J. F Knebel L. Spierer S. Clarke Micah M Murray Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Temporal aspects of the visuotactile congruency effect

We report an experiment designed to investigate the temporal dynamics of the visuotactile crossmodal congruency effect. Vibrotactile targets were presented randomly to the index finger (top side of a hand-held cube) or thumb (bottom side) of either hand while visual distractors were presented randomly from one of the same four possible locations. The stimulus onset asynchrony (SOA) between the vibrotactile target and the visual distractor was varied on a trial-by-trial basis. Participants made speeded discrimination responses regarding the elevation of the vibrotactile targets (i.e., upper versus lower) while trying to ignore the visual distractors. The largest crossmodal congruency effects (defined as the difference in performance between incongruent and congruent elevation distractor trials) were obtained when the visual distractor preceded the vibrotactile target by 50–100 ms, although significant effects were also reported when the distractor followed the target by as much as 100 ms. These results are discussed in terms of the conjoint influence of response competition, crossmodal perceptual interactions (i.e., the ventriloquism effect), and exogenous spatial attention on the crossmodal congruency effect. The distinct temporal signatures of each of these effects are also highlighted.

Rapid categorization of achromatic natural scenes: how robust at very low contrasts?

The human visual system is remarkably good at categorizing objects even in challenging visual conditions. Here we specifically assessed the robustness of the visual system in the face of large contrast variations in a high-level categorization task using natural images. Human subjects performed a go/no-go animal/nonanimal categorization task with briefly flashed grey level images. Performance was analysed for a large range of contrast conditions randomly presented to the subjects and varying from normal to 3% of initial contrast. Accuracy was very robust and subjects were performing well above chance level (approximately 70% correct) with only 10-12% of initial contrast. Accuracy decreased with contrast reduction but reached chance level only in the most extreme condition (3% of initial contrast). Conversely, the maximal increase in mean reaction time was approximately 60 ms (at 8% of initial contrast); it then remained stable with further contrast reductions. Associated ERPs recorded on correct target and distractor trials showed a clear differential effect whose amplitude and peak latency were correlated respectively with task accuracy and mean reaction times. These data show the strong robustness of the visual system in object categorization at very low contrast. They suggest that magnocellular information could play a role in ventral stream visual functions such as object recognition. Performance may rely on early object representations which lack the details provided subsequently by the parvocellular system but contain enough information to reach decision in the categorization task.

Effects of verbal and nonverbal interference on spatial and object visual working memory.

We tested the hypothesis that a verbal coding mechanism is necessarily engaged by object, but not spatial, visual working memory tasks. We employed a dual-task procedure that paired n-back working memory tasks with domain-specific distractor trials inserted into each interstimulus interval of the n-back tasks. In two experiments, object n-back performance demonstrated greater sensitivity to verbal distraction, whereas spatial n-back performance demonstrated greater sensitivity to motion distraction. Visual object and spatial working memory may differ fundamentally in that the mnemonic representation of featural characteristics of objects incorporates a verbal (perhaps semantic) code, whereas the mnemonic representation of the location of objects does not. Thus, the processes supporting working memory for these two types of information may differ in more ways than those dictated by the "what/where" organization of the visual system, a fact more easily reconciled with a component process than a memory systems account of working memory function.

Enhanced attention in rhesus monkeys as a common factor for the cognitive effects of drugs with abuse potential.

One of the common neurochemical features of many drugs of abuse is their ability to directly or indirectly enhance dopaminergic activity in the brain, particularly within the ventral tegmental-nucleus accumbens pathway. Dopaminergic pathways in the frontal and limbic cortex also may be targets for these agents, where pharmacological effects could result in heightened attention and/or support self-administration behavior. The purpose of this study was to determine whether drugs from differing pharmacological classes that exhibit abuse potential would share the ability to counter distractability in the delayed matching task. Well trained mature macaques performed a computer-assisted delayed matching-to-sample task which included trials associated with three delay intervals and randomly interspersed task-relevant distractors. Drug regimens included four to five doses and subjects were tested no more than twice per week. All but one of the six compounds (tomoxetine), on average, increased task accuracy for either non-distractor or distractor trials. It was evident that for several compounds, doses required to improve accuracy for non-distractor trials were routinely greater than the doses required to improve accuracy for distractor trials. Data for the individualized Best dose (based upon the subject's optimal level of accuracy during distractor trials) revealed statistically significant distractor-related improvements in task accuracy for the same five compounds. The relative efficacy for reversing distractor-induced decrements in task accuracy was estimated by the level of improvement with respect to baseline: nomifensine (31%)>nicotine (22%) approximately morphine (19%) approximately caffeine (19%) approximately methylphenidate (22%) >tomoxetine (9%). Tomoxetine (noradrenergic preferring) was the only compound that did not produce a significant improvement in accuracy. These results provide pharmacological support for the concept that attentional mechanisms may play an important role in the "environmental" associative aspects of drug seeking behavior, and as such they may provide the basis for treatment strategies aimed at preventing relapse in detoxified addicts.

Selective reaching: Evidence for multiple frames of reference.

Students participated in 3 experiments investigating the use of environment- and action-centered reference frames in selective reaching. They pointed to a green target appearing either with or without a red distractor. Target-distractor distance was manipulated, and distractor interference (difference between distractor trials and no-distractor trials) was measured in reaction time, movement time, and movement endpoint. Target-distractor distance determined the dominant frame of reference. Small distances evoked an environment-centered framework that encoded targets within an external context. Large distances evoked an action-centered framework that encoded targets relative to the start position of the hand. Results support the hypothesis that the brain represents spatial information in multiple frames of reference, with the dominant frame of reference being dependent on the task demands.

Response of neurons in the lateral intraparietal area to a distractor flashed during the delay period of a memory-guided saccade.

Recent experiments raised the possibility that the lateral intraparietal area (LIP) might be specialized for saccade planning. If this was true, one would expect a decreased sensitivity to irrelevant visual stimuli appearing late in the delay period of a memory-guided delayed-saccade task to a target outside the neurons' receptive fields. We trained two monkeys to perform a standard memory-guided delayed-saccade task and a distractor task in which a stimulus flashed for 200 ms at a predictable time 300-100 ms before the end of the delay period. We used two locations, one in the most active part of the receptive field and another well outside the receptive field. We used six kinds of trials randomly intermixed: simple delayed-saccade trials into or away from the receptive field and distractor trials with saccade target and distractor both in the receptive field, both out of the receptive field, or one at each location. This enabled us to study the response to the distractor as a function of the monkey's preparation of a memory-guided delayed-saccade task. We had assumed that the preparation of a saccade away from the receptive field would result in an attenuation of the response to the distractor, i.e., a distractor at the location of the saccade goal would evoke a greater response than when it appeared at a location far from the saccade goal. Instead we found that neurons exhibited either a normal or an enhanced visual response to the distractor during the memory period when the target flashed outside the receptive field. When the distractor flashed at the location of the saccade target, the response to the distractor was either unchanged or diminished. The response to a distractor away from the target location of a memory-guided saccade was even greater than the response to the same target when it was the target for the memory-guided saccade task. Immediate presaccadic activity did not distinguish between a saccade to the receptive field when there was no distractor and a distractor in the receptive field when the monkey made a saccade elsewhere. Nonetheless the distractor had no significant effect on the saccade latency, accuracy, or velocity despite the brisk response it evoked immediately before the saccade. We suggest that these results are inconsistent with a role for LIP in the specific generation of saccades, but they are consistent with a role for LIP in the generation of visual attention.

Brain Areas Involved in Rapid Categorization of Natural Images: An Event-Related fMRI Study

Event-related fMRI was used to investigate brain activation during a visual go/no-go categorization task based on colored photographs of natural scenes, similar to a previous ERP study by Thorpe et al. (1996, Nature 381: 520–522). Subjects had to press a key when an animal was present in the display. Stimuli were flashed for 33 ms using an intertrial interval of 5 s and a design that carefully balanced targets and distractors in a pseudo-random sequence. Activation produced by targets and distractors was compared with two different techniques, one based on correlations with the stimulation pattern, the other using simple t score statistics to compare selected scans. The contralateral primary motor cortex and the ipsilateral cerebellum were both more active following target trials than following distractors, thus confirming the sensitivity of the method. Differential activity was also seen in the posterior cingulate cortex, the fusiform, and the parahippocampic gyri. Activity in such structures could underlie the differential evoked-potentials reported previously in the same task. Surprisingly, in these visual structures, the signal was stronger following distractor trials than target ones. This result could be due to more prolonged processing on distractor trials. Alternatively, it could be that target detection induces strong activation of a small proportion of neurons, which, because of competitive inhibitory mechanisms, could result in a decrease in activity for the population as a whole. We suggest that this kind of mechanism could also account for the decreases in signal observed in perceptual priming experiments.

Alpha-2 adrenergic agonists decrease distractibility in aged monkeys performing the delayed response task.

With advancing age, monkeys become impaired on a test of spatial working memory, the delayed response task, and show increased susceptibility to interference from irrelevant stimuli (Bartus and Dean 1979). Alpha-2 adrenergic agonists such as clonidine and guanfacine have been shown to improve the delayed response performance of aged monkeys under standard testing conditions (e.g. Arnsten et al. 1988). The current study examined whether these drugs could protect the delayed response performance of aged monkeys when irrelevant stimuli were presented during the delay intervals. Aged monkeys were tested on the variable delayed response task with short delays to minimize memory demands and optimize performance on control (no interference) sessions. During interference sessions, distractors were presented during the delays on 9 of the 30 trials ("distractor" trials). If the aged monkeys had been pretreated with saline, performance was significantly disrupted by the irrelevant stimuli compared to matched saline control sessions. This impairment was not only evident on the 9 distractor trials, but on the 21 remaining "nondistractor" trials as well. However, if the aged monkeys had been pretreated with clonidine or guanfacine, performance was not impaired on the interference sessions. This beneficial effect of the alpha-2 agonists was most apparent on the nondistractor trials. Guanfacine was able to decrease the harmful effects of distraction without any apparent sedative side effects. Co-administration of the alpha-2 antagonists idazoxan or SKF104078 with clonidine blocked the protective effects of the agonist on delayed response performance, consistent with actions at alpha-2 adrenergic receptors. These findings suggest that alpha-2 agonists improve delayed response performance, at least in part, by helping to protect memory from irrelevant stimulation. Clonidine is already used in the treatment of Attention Deficit Disorder, and the current data suggest that guanfacine may also be useful in this regard.