Papers by Matthew Peterson
Nucleic acids research, Jan 4, 2015
Bacterial pathogens adapt to changing environments within their hosts, and the signaling molecule... more Bacterial pathogens adapt to changing environments within their hosts, and the signaling molecule adenosine 3', 5'-cyclic monophosphate (cAMP) facilitates this process. In this study, we characterized in vivo DNA binding and gene regulation by the cAMP-responsive protein CRP in M. bovis BCG as a model for tuberculosis (TB)-complex bacteria. Chromatin immunoprecipitation followed by deep-sequencing (ChIP-seq) showed that CRP associates with ∼900 DNA binding regions, most of which occur within genes. The most highly enriched binding region was upstream of a putative copper transporter gene (ctpB), and crp-deleted bacteria showed increased sensitivity to copper toxicity. Detailed mutational analysis of four CRP binding sites upstream of the virulence-associated Rv0249c-Rv0247c succinate dehydrogenase genes demonstrated that CRP directly regulates Rv0249c-Rv0247c expression from two promoters, one of which requires sequences intragenic to Rv0250c for maximum expression. The high...
Resuming after Interruption: Exploring the roles of spatial and goal memory
PsycEXTRA Dataset, 2009
The effect of saccade metrics on the corollary discharge contribution to perceived eye location
Journal of neurophysiology, Jan 11, 2015
Corollary discharge (CD) is hypothesized to provide the movement information (direction and ampli... more Corollary discharge (CD) is hypothesized to provide the movement information (direction and amplitude) required to compensate for the saccade induced disruptions to visual input. Here, we investigated to what extent these conveyed metrics influence perceptual stability in human subjects with a target displacement detection task. Subjects made saccades to targets located at different amplitudes (4°, 6° or 8°) and directions (horizontal or vertical). During the saccade the target disappeared and then reappeared at a shifted location either in the same direction or opposite to the movement vector. Subjects reported the target displacement direction and from these reports we determined the perceptual threshold for shift detection and estimate of target location. Our results indicate that the thresholds for all amplitudes and directions generally scaled with saccade amplitude. Additionally, subjects on average produced hypometric saccades with an estimated CD gain less than one. Finally,...
Enhancing multiple object tracking performance with noninvasive brain stimulation: a causal role for the anterior intraparietal sulcus
Frontiers in systems neuroscience, 2015
Multiple object tracking (MOT) is a complex task recruiting a distributed network of brain region... more Multiple object tracking (MOT) is a complex task recruiting a distributed network of brain regions. There are also marked individual differences in MOT performance. A positive causal relationship between the anterior intraparietal sulcus (AIPS), an integral region in the MOT attention network and inter-individual variation in MOT performance has not been previously established. The present study used transcranial direct current stimulation (tDCS), a form of non-invasive brain stimulation, in order to examine such a causal link. Active anodal stimulation was applied to the right AIPS and the left dorsolateral prefrontal cortex (DLPFC) (and sham stimulation), an area associated with working memory (but not MOT) while participants completed a MOT task. Stimulation to the right AIPS significantly improved MOT accuracy more than the other two conditions. The results confirm a causal role of the AIPS in the MOT task and illustrate that tDCS has the ability to improve MOT performance.
Brain research. Cognitive brain research, 2005
Preview benefit is an attentional phenomenon that enables observers to selectively search through... more Preview benefit is an attentional phenomenon that enables observers to selectively search through new information in the visual field. In a preview search task, objects are presented in two sets, separated by a time interval (preview interval), and with the second set (new objects) containing the target. Event-related brain potentials (ERPs) were used to investigate whether preview benefit occurs via maintenance of inhibition of the old objects during the preview interval. ERPs time-locked to a color probe indicated that the old objects were actively attended rather than inhibited during the preview interval. Follow-up behavioral experiments produced converging results. The results suggest that, although participants might be using inhibition at later stages of the preview interval, they are not maintaining inhibition on the old objects throughout most of the preview interval.
If you are a design researcher or graduate student who enters the keyword "branding" into the typ... more If you are a design researcher or graduate student who enters the keyword "branding" into the typical university library catalogue search engine, you will be as likely to yield books on cattle as on corporate identity. Or if you are a practitioner and want to locate one of the doctoral dissertations on design, completed in a handful of research-oriented PhD programs around the world, you will need a pretty good idea of the title or researcher's name to find it. And if you are design faculty and find it necessary to access work in non-design disciplines that might be relevant to your scholarship, you will be on your own to winnow the titles from hundreds of books within a Library of Congress topical category to find something truly useful to design. In other words, there are no current databases on design research and few design-sensitive keywords that drive other disciplinary search engines. This work proposes a solution to that dilemma.
Memory mechanisms make search efficient during static and dynamic search
PsycEXTRA Dataset, 2000
Working memory capacity (WMC) is generally referred to as a quantitative measure of the ability t... more Working memory capacity (WMC) is generally referred to as a quantitative measure of the ability to maintain relevant information while performing unrelated tasks . Although studies have shown that WMC can vary by individual , performance can be taxed by varying degrees of subjective workload depending on the task parameters. Most studies have shown task performance benefits for individuals with high working memory capacity, with some exceptions for individuals with low working memory capacity . Kane and colleagues (2006) tested the relationship of WMC and executive attention control and found no relationship with individual differences in WMC and performance on visual search tasks, namely on feature-absence, conjunction, and spatial configuration search tasks. However, other studies have found that loading
Explicit memory for rejected distractors during visual search
Visual Cognition, 2006
Page 1. Explicit memory for rejected distractors during visual search Melissa R. Beck and Matthew... more Page 1. Explicit memory for rejected distractors during visual search Melissa R. Beck and Matthew S. Peterson Psychology Department, George Mason University, Fairfax, Virginia, USA Walter R. Boot Beckman Institute and Department ...
Oculomotor behaviour in visual search for multiple targets
Visual Cognition, 2006
Page 1. Oculomotor behaviour in visual search for multiple targets Jason S. McCarley, Arthur F. K... more Page 1. Oculomotor behaviour in visual search for multiple targets Jason S. McCarley, Arthur F. Kramer, and Walter R. Boot University of Illinois at Urbana-Champaign, IL, USA Matthew S. Peterson George Mason University, Fairfax, VA, USA ...
Vision Research, 2009
Scrutiny of the numerous physiology and imaging studies of visual attention reveal that integrati... more Scrutiny of the numerous physiology and imaging studies of visual attention reveal that integration of results from neuroscience with the classic theories of visual attention based on behavioral work is not simple. The different subfields have pursued different questions, used distinct experimental paradigms and developed diverse models. The purpose of this review is to use statistical decision theory and computational modeling to relate classic theories of attention in psychological research to neural observables such as mean firing rate or functional imaging BOLD response, tuning functions, Fano factor, neuronal index of detectability and area under the receiver operating characteristic (ROC). We focus on cueing experiments and attempt to distinguish two major leading theories in the study of attention: limited resources model/increased sensitivity vs. selection/differential weighting. We use Bayesian ideal observer (BIO) modeling, in which predictive cues or prior knowledge change the differential weighting (prior) of sensory information to generate predictions of behavioral and neural observables based on Gaussian response variables and Poisson process neural based models. The ideal observer model can be modified to represent a number of classic psychological theories of visual attention by including hypothesized human attentional limited resources in the same way sequential ideal observer analysis has been used to include physiological processing components of human spatial vision (Geisler, W. S. (1989). Sequential ideal-observer analysis of visual discrimination. Psychological Review 96, 267-314.). In particular we compare new biologically plausible implementations of the BIO and variant models with limited resources. We find a close relationship between the behavioral effects of cues predicted by the models developed in the field of human psychophysics and their neuron-based analogs. Critically, we show that cue effects on experimental observables such as mean neural activity, variance, Fano factor and neuronal index of detectability can be consistent with the two major theoretical models of attention depending on whether the neuron is assumed to be computing likelihoods, log-likelihoods or a simple model operating directly on the Poisson variable. Change in neuronal tuning functions can also be consistent with both theories depending on whether the change in tuning is along the dimension being experimentally cued or a different dimension. We show that a neuron's sensitivity appropriately measured using the area under the Receive Operating Characteristic curve can be used to distinguish across both theories and is robust to the many transformations of the decision variable. We provide a summary table with the hope that it might provide some guidance in interpreting past results as well as planning future studies.
Landmarks help guide attention during visual search
Spatial Vision, 2004
Using a novel visual search paradigm McCarley et al. (2003) concluded that the oculomotor system ... more Using a novel visual search paradigm McCarley et al. (2003) concluded that the oculomotor system keeps a history of 3-4 previously attended objects. However, their displays were visually sparse, denying participants structural information which might be used during normal search. This might have underestimated memory capacity. To examine this possibility, we included landmarks in the same search paradigm. Previously examined items were re-examined less frequently when landmarks were present compared to when they were absent. Results indicate that objects in the environment that share no features with search items are used as external support to aid memory in guiding visual search.
Psychonomic Bulletin & Review, 2008
Automatic and intentional memory processes in visual search
Psychonomic Bulletin & Review, 2004
Previous research has indicated that saccade target selection during visual search is influenced ... more Previous research has indicated that saccade target selection during visual search is influenced by scanning history. Already inspected items are less likely to be chosen as saccade targets as long as the number intervening saccades is small. Here, we adapted Jacoby's (1991) process dissociation procedure to assess the role of intentional and automatic processes in saccade target selection. Results indicate a large automatic component biasing participants to move their eyes to unexamined locations. However, an intentional component allowed participants to both reinspect old items and aid their selection of new items. A second experiment examined inhibition of return (IOR) as a candidate for the observed automatic component. IOR was found for items that had been previously examined. It is concluded that both automatic and intentional memory traces are available to guide the eyes during search.
Psychonomic Bulletin & Review, 2002
Training Effects on Dual-Task Performance: Are There Age-Related Differences in Plasticity of Attentional Control?
Psychology and Aging, 2005
A number of studies have suggested that attentional control skills required to perform 2 tasks co... more A number of studies have suggested that attentional control skills required to perform 2 tasks concurrently become impaired with age (A. A. Hartley, 1992; J. M. McDowd & R. J. Shaw, 2000). A. A. Hartley (2001) recently observed that the age-related differences in dual-task performance were larger when the 2 tasks required similar motor responses. The present study examined the extent to which age-related deficits in dual-task performance or time sharing--in particular, dual-task performance of 2 discrimination tasks with similar motor requirements--can be moderated by training. The results indicate that, even when the 2 tasks required similar motor responses, both older and younger adults could learn to perform the tasks faster and more accurately. Moreover, the improvement in performance generalized to new task combinations involving new stimuli. Therefore, it appears that training can substantially improve dual-task processing skills in older adults.
Psychology and Aging, 2004
This study examined age differences in task switching using prosaccade and antisaccade tasks. Sig... more This study examined age differences in task switching using prosaccade and antisaccade tasks. Significant specific and general switch costs were found for both young and old adults, suggesting the existence of 2 types of processes: those responsible for activation of the currently relevant task set and deactivation of the previously relevant task set and those responsible for maintaining more than 1 task active in working memory. Contrary to the findings of previous research, which used manual response tasks with arbitrary stimulus-response mappings to study task-switching performance, no age-related deficits in either type of switch costs were found. These data suggest age-related sparing of task-switching processes in situations in which memory load is low and stimulus-response mappings are well learned.
Aging and the Strategic Control of the Fixation Offset Effect
Psychology and Aging, 2004
A study was conducted to examine potential age-related differences in the strategic control of ex... more A study was conducted to examine potential age-related differences in the strategic control of exogenous and endogenous saccades within the context of the fixation offset effect (FOE; i.e., faster saccades when a fixation point is removed than when it is left on throughout a trial). Subjects were instructed to make rapid saccades either on the basis of a suddenly appearing peripheral visual stimulus (exogenous saccade) or in response to a tone (endogenous saccade). On half of the trials the fixation point was removed simultaneously with the occurrence of the cue stimulus. Subjects' preparatory set was varied by manipulating the proportion of saccades generated to a visual and auditory stimulus within a trial block. Young and old adults both produced FOEs, and the FOEs were strategically modulated by preparatory set. The data are discussed in terms of aging and oculomotor control.
Psychological Science, 2001
By monitoring subjects' eye movements during a visual search task, we examined the possibility th... more By monitoring subjects' eye movements during a visual search task, we examined the possibility that the mechanism responsible for guiding attention during visual search has no memory for which locations have already been examined. Subjects did reexamine some items during their search, but the pattern of revisitations did not fit the predictions of the memoryless search model. In addition, a large proportion of the refixations were directed at the target, suggesting that the revisitations were due to subjects' remembering which items had not been adequately identified. We also examined the patterns of fixations and compared them with the predictions of a memoryless search model. Subjects' fixation patterns showed an increasing hazard function, whereas the memoryless model predicts a flat function. Lastly, we found no evidence suggesting that fixations were guided by amnesic covert scans that scouted the environment for new items during fixations. Results do not support the claims of the memoryless search model, and instead suggest that visual search does have memory.
Psychological Science, 2003
Research has demonstrated that oculomotor visual search is guided by memory for which items or lo... more Research has demonstrated that oculomotor visual search is guided by memory for which items or locations within a display have already been inspected. In the study reported here, we used a gaze-contingent search paradigm to examine properties of this memory. Data revealed a memory buffer for search history of three to four items. This buffer was effected in part by a space-based trace attached to a location independently of whether the object that had been seen at that position remained visible, and was subject to interference from other stimuli seen in the course of a trial.
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Papers by Matthew Peterson