Scanning memory for multidimensional stimuli with extended practice

The present study examined age-related differences in multisensory integration and the effect of spatial disparity on the sound-induced flash illusion—-an illusion used in previous research to assess age-related differences in multisensory integration. Prior to participation in the study, both younger and older participants demonstrated their ability to detect 1–2 visual flashes and 1–2 auditory beep presented unimodally. After passing the pre-test, participants were then presented 1–2 flashes paired with 0–2 beeps that originated from one of five speakers positioned equidistantly 100cm from the participant. One speaker was positioned directly below the screen, two speakers were positioned 50cm to the left and right from the center of the screen, and two more speakers positioned to the left and right 100cm from the center of the screen. Participants were told to report the number of flashes presented and to ignore the beeps. Both age groups showed a significant effect of the beeps on the perceived number of flashes. However, neither younger nor older individuals showed any significant effect of spatial disparity on the sound-induced flash illusion. The presence of a congruent number of beeps increased accuracy for both older and younger individuals. Reaction time data was also analyzed. As expected, older individuals showed significantly longer reaction times when compared to younger individuals. In addition, both older and younger individuals showed a significant increase in reaction time for fusion trials, where two flashes and one beep are perceived as a single flash, as compared to congruent single flash trials. This increase in reaction time was not found for fission trials, where one flash and two beeps were perceived as two flashes. This suggests that processing may differ for the two forms for fission as compared to fusion illusions.

It has been suggested that interference in symbolically cued bimanual reaction time tasks is caused primarily by the perceptual processing of stimuli and not by motor preparation of the required movements. Here subjects made movements of the right and left index fingers that varied in their spatial and motor congruence. Spatial congruence was manipulated by presenting symbolic cues (i.e., pairs of letters) on a computer screen cueing the required movement directions. Motor congruence was manipulated by altering hand orientation. Results showed that interference occurs at both the stage of stimulus processing and the stage of motor preparation. These effects were reflected in the latencies of the different bimanual movements with both motor incongruence and spatial incongruence causing significant increases in reaction time. However, spatially incongruent movements that were made in response to incongruent visual cues demonstrated changes in reaction time that were more than double those of movements that required simultaneous activation of nonhomologous muscles. Therefore in symbolically cued bimanual reaction-time tasks, although both motor and spatial constraints operate, there is a clear dominance of spatial incongruence on performance. While motor congruence effects are likely due to cross-facilitation in corticospinal pathways, spatial incongruence effects are probably due to interference between the mechanisms that identify incongruent stimuli and translate these cues into the appropriate movements.

Monkeys have been introduced as model organisms to study neural correlates of numerical competence, but many of the behavioral characteristics of numerical judgments remain speculative. Thus, we analyzed the behavioral performance of two rhesus monkeys judging the numerosities 1 to 7 during a delayed match-to-sample task. The monkeys showed similar discrimination performance irrespective of the exact physical appearance of the stimuli, confirming that performance was based on numerical information. Performance declined smoothly with larger numerosities, and reached discrimination threshold at numerosity "4." The nonverbal numerical representations in monkeys were based on analog magnitudes, object tracking process ("subitizing") could not account for the findings because the continuum of small and large numbers shows a clear Weber fraction signature. The lack of additional scanning eye movements with increasing set sizes, together with indistinguishable neuronal response latencies for neurons with different preferred numerosities, argues for parallel encoding of numerical information. The slight but significant increase in reaction time with increasing numerosities can be explained by task difficulty and consequently time-consuming decision processes. The behavioral results are compared to single-cell recordings from the prefrontal cortex in the same subjects. Models for numerosity discrimination that may account for these results are discussed.

The contribution of α 2-adrenoceptor and opioid receptor mechanisms to antinociception differs in Lewis and Fischer 344 rats

Event Abstract Back to Event The influence of subliminal threat cues on successful response inhibition Catherine Orr1*, Hugh Garavan2, 3, Karen Weierstall2 and Robert Hester1 1 University of Melbourne, Melbourne School of Psychological Sciences, Australia 2 University of Vermont, Psychology, United States 3 Trinity College Dublin, Ireland The relationship between automatic, threat-related processes and the frontoparietal control network in response inhibition was investigated. It has previously been shown that task irrelevant fearful faces disrupt ongoing task performance, likely due to the need to interrupt or change the planned motor action in response to an unexpected threat signal. It is not clear, however, how this process is related to deliberate response inhibition at a behavioural and neural level. During fMRI, we administered a Go/No-go task in which presentation of the No-go stimulus could be preceded by a subliminally presented face cue. The period following a fearful face cue (cue period) was characterised by a significant increase in reaction time (RT) relative to the cue period following a neutral face. Slowing of RT during the cue period was associated with increased activity in frontal and parietal regions previously implicated in successful response inhibition and motor control, including the dorsolateral prefrontal cortex (DLPFC), supplementary motor area (SMA), and cingulate gyrus. Psychophysiological interaction analysis revealed that functional connectivity between the amygdala and PFC was associated with post-cue slowing for fearful cues. These measures were not, however, associated with more successful inhibition performance during fearfully cued blocks than either neutrally cued or uncued blocks. Taken together, our results suggest that threat perception may influence brain systems involved in motor control; although this network partially overlaps with the regions required for voluntary response inhibition, in the current study the action of this network was not sufficient to improve inhibition performance. Acknowledgements NHMRC Grant 1008044 ARC Grant DP1092852 References Hester, R. L., Murphy, K., Foxe, J. J., Foxe, D. M., Javitt, D. C., & Garavan, H. (2004). Predicting success: patterns of cortical activation and deactivation prior to response inhibition. Journal of Cognitive Neuroscience, 16(5), 776-785. Kim, M. J., Loucks, R., Neta, M., Davis, F. C., Oler, J., Mazzulla, E., & Whalen, P. (2010). Behind the mask: the influence of mask-type on amygdala response to fearful faces. Social Cognitive & Affective Neuroscience, 5(4), 363-368. Sagaspe, P., Schwartz, S., & Vuilleumier, P., (2011). Fear and stop: A role for the amygdala in motor inhibition by emotional signals. Neuroimage, 55(4), 1825-1835. Keywords: Subliminal threat cues, response inhibition, functional MRI (fMRI), cognitive control, Amygdala Conference: ACNS-2012 Australasian Cognitive Neuroscience Conference, Brisbane, Australia, 29 Nov - 2 Dec, 2012. Presentation Type: Poster Presentation Topic: Executive Processes Citation: Orr C, Garavan H, Weierstall K and Hester R (2012). The influence of subliminal threat cues on successful response inhibition. Conference Abstract: ACNS-2012 Australasian Cognitive Neuroscience Conference. doi: 10.3389/conf.fnhum.2012.208.00188 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: 14 Oct 2012; Published Online: 17 Nov 2012. * Correspondence: Dr. Catherine Orr, University of Melbourne, Melbourne School of Psychological Sciences, Parkville, VIC, 3010, Australia, corr1@uvm.edu 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 Catherine Orr Hugh Garavan Karen Weierstall Robert Hester Google Catherine Orr Hugh Garavan Karen Weierstall Robert Hester Google Scholar Catherine Orr Hugh Garavan Karen Weierstall Robert Hester PubMed Catherine Orr Hugh Garavan Karen Weierstall Robert Hester 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.

This study investigated the effect of variable interstimulus intervals (ISIs) on behavioral reaction time (RT) and on the latency and amplitude of the auditory P300 using an auditory continuous performance task (ACPT) paradigm. Twenty subjects were instructed to respond to common stimuli and ignore a rare stimulus. Common stimuli were 1000-, 1500-, and 2000-Hz pure tones. The rare stimulus was a 250-Hz pure tone. ISIs of 1, 2, and 4 seconds were used for this investigation. A significant correlation between ISI, reaction time, P300 latency, correct rejections, and false alarm rates was found. A significant correlation between P300 latency, P300 amplitude, correct rejections, and false alarm rates was also observed. Likewise, a statistically significant increase in reaction time (RT) was observed as ISI increased. The ACPT paradigm in conjunction with the auditory P300 response can measure both behavioral and electrophysiologic changes that occur during active auditory attention and auditory cognitive processing tasks.

Detecting signs for an increased level of risk during driving are critical for the effective prevention of road traffic accidents. The current study searched for literature through major databases such as PubMed, EBSCO, IEEE, and ScienceDirect. A total of 14 articles that measured P300 components in relation to driving tasks were included for a systematic review and meta-analysis. The risk factors investigated in the reviewed articles were summarized in five categories, including reduced attention, distraction, alcohol, challenging situations on the road, and negative emotion. A meta-analysis was conducted at both behavioral and neural levels. Behavioral performance was measured by the reaction time and driving performance, while the neural response was measured by P300 amplitude and latency. A significant increase in reaction time was identified when drivers were exposed to the risk factors. In addition, the significant effects of a reduced P300 amplitude and prolonged P300 latency indicated a reduced capacity for cognitive information processing. There was a tendency of driving performance decrement in relation to the risk factors, however, the effect was non-significant due to considerable variations and heterogeneity across the included studies. The results led to the conclusion that the P300 amplitude and latency are reliable indicators and predictors of the increased risk in driving. Future applications of the P300-based brain–computer interface (BCI) system may make considerable contributions toward preventing road traffic accidents.

Ensemble perception-the encoding of objects by their group properties-is known to be resistant to outlier noise. However, this resistance is somewhat paradoxical: how can the visual system determine which stimuli are outliers without already having derived statistical properties of the ensemble? A simple solution would be that ensemble perception is not a simple, one-step process; instead, outliers are detected through iterative computations that identify items with high deviance from the mean and reduce their weight in the representation over time. Here we tested this hypothesis. In Experiment 1, we found evidence that outliers are discounted from mean orientation judgments, extending previous results from ensemble face perception. In Experiment 2, we tested the timing of outlier rejection by having participants perform speeded judgments of sets with or without outliers. We observed significant increases in reaction time (RT) when outliers were present, but a decrease compared to no-outlier sets of matched range suggesting that range alone did not drive RTs. In Experiment 3 we tested the timing by which outlier noise reduces over time. We presented sets for variable exposure durations and found that noise decreases linearly over time. Altogether these results suggest that ensemble representations are optimized through iterative computations aimed at reducing noise. The finding that ensemble perception is an iterative process provides a useful framework for understanding contextual effects on ensemble perception. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Network pharmacology, in-silico and in-vivo studies for analgesic and antipyretic activities of Haplanthodes tentaculata (L) leaves.

The effects of a five-digit memory load on joke and lexical decision tasks were measured. 72 college students read jokes ending with punchlines, consistent endings, or inconsistent endings and decided whether the endings produced jokes. Memory-loaded subjects were slower than nonloaded subjects, particularly on inconsistent endings which were surprising but not coherent with the body of the joke. Memory load had no effect on lexical decision time and did not interact with word frequency. The results supported the claim that working memory serves an integrating role in language comprehension.

The effect of memory load on the cognitive pupillary response among 16 young adults and 16 older adults was investigated. Mean pupil dilation and reaction time were measured during a Sternberg memory-search task, which involved six levels of memory load. A classic interaction pattern was obtained in which the reaction times of the elderly participants increased more as a function of memory load than the reaction times of the young participants. In the encoding phase of the experiment, mean dilation increased with memory load. No age differences were observed here. In the search phase of the experiment, however, mean pupil dilation was considerably greater in the young than in the elderly participants. Moreover, mean dilation of the older participants was not sensitive to memory load, whereas mean dilation increased as a function of memory load in the young participants. The results suggest that the usefulness of the pupillary response as a correlate of subtle fluctuations in memory load diminishes with old age.

Short-term recovery sleep attenuates the impairment of response inhibition after total sleep deprivation: Evidence from an event-related potentials study.

Two experiments examined visual search performance both by itself and in conjuction with concurrent, non-visual activity to assess the involvement of attention in the array size effect. Short-term retention was the concurrent activity in Experiment i, and changing S-R mapping during search was the activity in Experiment n. In both experiments, reaction time increased with array size (4, 8, or 12 letters) and concurrent activity, but their effects were additive. The results were interpreted as confirming predictions derived from unlimited-capacity theories of visual search and are related to findings with similar procedures in the memory search paradigm.

The effect of rehearsal rate and memory load on verbal working memory

We investigated the effect of memory load on attentional control using the Reading Span Test (RST), a task that requires working memory capacity. Previous studies have shown that a shortage of working memory resources leads to a deficit of inhibition of taskirrelevant information and that memory load affects eye movement control. Here, we recorded eye movement and integrated it with RST performance. Total fixation time and the number of regressions showed a memory load effect with the to-be-remembered word, and RST performance was also affected under high memory load. We concluded that a shortage of working memory resources caused by memory load prevents flexible eye movement control and may cause a deficit in inhibitory control based on intrusion errors.