A New Foreperiod Effect on Intertrial Phase Coherence. Part I: Existence and Behavioral Relevance

2018 ◽  
Vol 30 (9) ◽  
pp. 2348-2383 ◽  
Author(s):  
Joaquin Rapela ◽  
Marissa Westerfield ◽  
Jeanne Townsend
Keyword(s):  
Reaction Time ◽  
Warning Signal ◽  
Phase Coherence ◽  
Warning Signals ◽  
Temporal Expectation ◽  
Relevant Effect ◽  
Phase Alignment ◽  
Multiple Trials ◽  
Trial Basis ◽  
Eeg Recordings

This letter makes scientific and methodological contributions. Scientifically, it demonstrates a new and behaviorally relevant effect of temporal expectation on the phase coherence of the electroencephalogram (EEG). Methodologically, it introduces novel methods to characterize EEG recordings at the single-trial level. Expecting events in time can lead to more efficient behavior. A remarkable finding in the study of temporal expectation is the foreperiod effect on reaction time, that is, the influence on reaction time of the delay between a warning signal and a succeeding imperative stimulus to which subjects are instructed to respond as quickly as possible. Here we study a new foreperiod effect in an audiovisual attention-shifting oddball task in which attention-shift cues directed the attention of subjects to impendent deviant stimuli of a given modality and therefore acted as warning signals for these deviants. Standard stimuli, to which subjects did not respond, were interspersed between warning signals and deviants. We hypothesized that foreperiod durations modulated intertrial phase coherence (ITPC, the degree of phase alignment across multiple trials) evoked by behaviorally irrelevant standards and that these modulations are behaviorally meaningful. Using averaged data, we first observed that ITPC evoked by standards closer to the warning signal was significantly different from that evoked by standards further away from it, establishing a new foreperiod effect on ITPC evoked by standards. We call this effect the standard foreperiod (SFP) effect on ITPC. We reasoned that if the SFP influences ITPC evoked by standards, it should be possible to decode the former from the latter on a trial-by-trial basis. We were able to do so showing that this effect can be observed in single trials. We demonstrated the behavioral relevance of the SFP effect on ITPC by showing significant correlations between its strength and subjects' behavioral performance.

scholarly journals A new foreperiod effect on single-trial phase coherence. Part I: existence and relevance

2016 ◽  
Author(s):  
Joaquin Rapela ◽  
Marissa Westerfield ◽  
Jeanne Townsend ◽  
Scott Makeig
Keyword(s):  
Reaction Times ◽  
Stimulus Presentation ◽  
Warning Signal ◽  
Error Rates ◽  
Phase Coherence ◽  
Oscillatory Activity ◽  
Single Trial ◽  
Foreperiod Duration ◽  
Trial Basis ◽  
Trial Phase

AbstractExpecting events in time leads to more efficient behavior. A remarkable early finding in the study of temporal expectancy is the foreperiod effect on reaction times; i.e., the fact that the time period between a warning signal and an impendent stimuli, to which subjects are instructed to respond as quickly as possible, influences reaction times. Recently it has been shown that the phase of oscillatory activity preceding stimulus presentation is related to behavior. Here we connect both of these findings by reporting a novel foreperiod effect on the inter-trial phase coherence triggered by a stimulus to which subjects do not respond. Until now, inter-trial phase coherence has been used to describe a regularity in the phases of groups of trials. We propose a single-trial measure of inter-trial phase coherence and prove its soundness. Equipped with this measure, and using a multivariate decoding method, we demonstrate that the foreperiod duration modulates single-trial phase coherence. In principle, this modulation could be an artifact due to the decoding method used to detect it. We show that this is not the case, since the modulation can also be observed with a very simple averaging method. Although real, the single-trial modulation of inter-trial phase coherence by the foreperiod duration could just reflect a nuisance in our data. We argue against this possibility by showing that the strength of the modulation correlates with subjects’ behavioral measures, both error rates and mean-reaction times. We anticipate that the new foreperiod effect on inter-trial phase coherence, and the decoding method used here to detect it, will be important tools to understand cognition at the single-trial level. In Part II of this manuscript, we support this claim, by showing that attention modulates the strength of the new foreperiod effect in a trial-by-trial basis.

Simple reaction time as a measure of global attention in Alzheimer's disease

1995 ◽  
Vol 1 (1) ◽  
pp. 56-61 ◽  
Author(s):  
Mary Sano ◽  
Wilma Rosen ◽  
Yaakov Stern ◽  
Jeffrey Rosen ◽  
Richard Mayeux
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Reaction Time ◽  
Simple Reaction Time ◽  
Warning Signal ◽  
Control Group ◽  
Warning Signals ◽  
Attentional Processes ◽  
Simple Reaction ◽  
Response Stimulus

AbstractAlzheimer's disease (AD) is characterized by progressive decline in memory, language and other cognitive functions. Deficits in attentional processes have also been suggested. A simple reaction time (RT) task was used to assess global attention in AD. The length and consistency of a warning signal given prior to the response stimulus were manipulated to determine if patients with AD and age-matched controls benefit from predictability in RT tasks. Overall reaction time was slower in the AD group than in the and control group. Both groups demonstrated significant improvement in RT with long warning signals compared to short warning signals, but only the control group benefited from the consistency of the warning. (JINS, 1995, I, 56–61.)

Development of Candidate New Emergency Warning Signals (EWS) to Improve Railroad Safety

2017 ◽  
Author(s):  
Jason Ross ◽  
Tom Campbell ◽  
Basant Parida ◽  
Mark Arnoldy ◽  
Tarek Omar
Keyword(s):  
Reaction Time ◽  
Literature Review ◽  
Response Time ◽  
Signal Detection ◽  
Warning Signal ◽  
Air Pressure ◽  
Acoustic Measurements ◽  
Warning Signals ◽  
Railroad Safety ◽  
Sense Of Urgency

From the original “steam trumpet” built for locomotives in 1832 by the Leicester and Swannington Railway to modern air-pressure horns, train warning signals have not changed significantly in nearly 200 years. The effectiveness of train warning signals has been of particular concern for trespassers listening to music with headphones. The authors have conducted research as part of a Federal Railroad Administration program to design and assess the effectiveness of candidate new emergency warning signal (EWS) sounds. This paper summarizes a literature review to understand the needs for a new EWS sound and principles of audible signal detection. Acoustic measurements were conducted of headphones to understand in-ear music levels and active and passive sound attenuation. Candidate EWS sounds were developed with a goal of maintaining the identification of a train approaching and increasing the sense of urgency and response time for trespassers to vacate the tracks. Testing of candidate EWS sounds was conducted in an audio booth and on-board a moving locomotive. The research results have shown that a new EWS sound can maintain the association of a train approaching, increase the sense of urgency, reduce the reaction time for trespassers to vacate the tracks and improve safety on railroad corridors.

Preferred Hand and Steadiness of Reaction Time

1976 ◽  
Vol 42 (3) ◽  
pp. 983-988 ◽  
Author(s):  
R. Nakamura ◽  
R. Taniguchi ◽  
Y. Oshima
Keyword(s):  
Reaction Time ◽  
Warning Signal ◽  
Experimental Conditions ◽  
Two Factors

RT and its left/right difference of both biceps muscles were measured by electromyogram (EMG) in the bilateral simultaneous flexion of elbows using 11 left- and 13 right-handed subjects under four conditions which were combinations of two factors: warning signal; presence or absence of a fore-period, and position of limbs; elbow 90° or 135°. EMG-RT and its left/right difference were influenced by these factors. The effects of warning and position of limbs were not the same on the preferred and non-preferred hands. It was assumed that EMG-RTs of biceps in the preferred hand were less influenced by these experimental conditions.

scholarly journals Stabilizing selection on individual pattern elements of aposematic signals

2017 ◽  
Vol 284 (1861) ◽  
pp. 20170926 ◽  
Author(s):  
Anne E. Winters ◽  
Naomi F. Green ◽  
Nerida G. Wilson ◽  
Martin J. How ◽  
Mary J. Garson ◽  
...  
Keyword(s):  
Pattern Analysis ◽  
Marine Organism ◽  
Warning Signal ◽  
Colour Pattern ◽  
Stabilizing Selection ◽  
Warning Signals ◽  
Fish Predator ◽  
Selection For ◽  
Aposematic Signals ◽  
Behavioural Experiments

Warning signal variation is ubiquitous but paradoxical: low variability should aid recognition and learning by predators. However, spatial variability in the direction and strength of selection for individual elements of the warning signal may allow phenotypic variation for some components, but not others. Variation in selection may occur if predators only learn particular colour pattern components rather than the entire signal. Here, we used a nudibranch mollusc, Goniobranchus splendidus , which exhibits a conspicuous red spot/white body/yellow rim colour pattern, to test this hypothesis. We first demonstrated that secondary metabolites stored within the nudibranch were unpalatable to a marine organism. Using pattern analysis, we demonstrated that the yellow rim remained invariable within and between populations; however, red spots varied significantly in both colour and pattern. In behavioural experiments, a potential fish predator, Rhinecanthus aculeatus , used the presence of the yellow rims to recognize and avoid warning signals. Yellow rims remained stable in the presence of high genetic divergence among populations. We therefore suggest that how predators learn warning signals may cause stabilizing selection on individual colour pattern elements, and will thus have important implications on the evolution of warning signals.

scholarly journals Linking the evolution and form of warning coloration in nature

2011 ◽  
Vol 279 (1728) ◽  
pp. 417-426 ◽  
Author(s):  
Martin Stevens ◽  
Graeme D. Ruxton
Keyword(s):  
Mate Choice ◽  
Evolutionary Ecology ◽  
Classical System ◽  
Warning Signal ◽  
Current Understanding ◽  
Warning Coloration ◽  
Warning Signals ◽  
Initial Evolution ◽  
Mechanistic Basis ◽  
Future Work

Many animals are toxic or unpalatable and signal this to predators with warning signals (aposematism). Aposematic appearance has long been a classical system to study predator–prey interactions, communication and signalling, and animal behaviour and learning. The area has received considerable empirical and theoretical investigation. However, most research has centred on understanding the initial evolution of aposematism, despite the fact that these studies often tell us little about the form and diversity of real warning signals in nature. In contrast, less attention has been given to the mechanistic basis of aposematic markings; that is, ‘what makes an effective warning signal?’, and the efficacy of warning signals has been neglected. Furthermore, unlike other areas of adaptive coloration research (such as camouflage and mate choice), studies of warning coloration have often been slow to address predator vision and psychology. Here, we review the current understanding of warning signal form, with an aim to comprehend the diversity of warning signals in nature. We present hypotheses and suggestions for future work regarding our current understanding of several inter-related questions covering the form of warning signals and their relationship with predator vision, learning, and links to broader issues in evolutionary ecology such as mate choice and speciation.

scholarly journals Early warning signals of regime shifts in coupled human–environment systems

2016 ◽  
Vol 113 (51) ◽  
pp. 14560-14567 ◽  
Author(s):  
Chris T. Bauch ◽  
Ram Sigdel ◽  
Joe Pharaon ◽  
Madhur Anand
Keyword(s):  
Early Warning ◽  
Warning Signal ◽  
Regime Shifts ◽  
Dynamical Regime ◽  
Ecological Data ◽  
Warning Signals ◽  
Early Warning Signals ◽  
Human Environment ◽  
Environment Model ◽  
External Conditions

In complex systems, a critical transition is a shift in a system’s dynamical regime from its current state to a strongly contrasting state as external conditions move beyond a tipping point. These transitions are often preceded by characteristic early warning signals such as increased system variability. However, early warning signals in complex, coupled human–environment systems (HESs) remain little studied. Here, we compare critical transitions and their early warning signals in a coupled HES model to an equivalent environment model uncoupled from the human system. We parameterize the HES model, using social and ecological data from old-growth forests in Oregon. We find that the coupled HES exhibits a richer variety of dynamics and regime shifts than the uncoupled environment system. Moreover, the early warning signals in the coupled HES can be ambiguous, heralding either an era of ecosystem conservationism or collapse of both forest ecosystems and conservationism. The presence of human feedback in the coupled HES can also mitigate the early warning signal, making it more difficult to detect the oncoming regime shift. We furthermore show how the coupled HES can be “doomed to criticality”: Strategic human interactions cause the system to remain perpetually in the vicinity of a collapse threshold, as humans become complacent when the resource seems protected but respond rapidly when it is under immediate threat. We conclude that the opportunities, benefits, and challenges of modeling regime shifts and early warning signals in coupled HESs merit further research.

scholarly journals Visual Warning Signals Optimized for Human Perception: What the Eye Sees Fastest

2005 ◽  
Vol 2 (1) ◽  
pp. 45-52 ◽  
Author(s):  
B. L. Gros ◽  
D. S. Greenhouse ◽  
T. E. Cohn
Keyword(s):  
Human Perception ◽  
Warning Signal ◽  
Sensitivity Function ◽  
Visual Signals ◽  
Temporal Contrast ◽  
Warning Signals ◽  
Moving Stimuli ◽  
Classic Problem ◽  
Speed Advantage ◽  
Spatio Temporal

This study aimed to answer the question of how to design a visual warning signal that is most easily seen and produces the quickest reaction time. This is a classic problem of bionic optimization—if one knows the properties of the receiver one can most easily find a suitable solution. Because the peak of the spatio-temporal contrast sensitivity function of the human visual system occurs at non-zero spatial and temporal frequencies, it is likely that movement enhances the detectability of threshold visual signals. Earlier studies employing extended drifting sinewave gratings bear out this prediction. We have studied the ability of human observers to detect threshold visual signals for both moving and stationary stimuli. We used discrete, localized signals such as might be employed in aerospace or automotive warning signal displays. Moving stimuli show a superior detectability to non-moving stimuli of the same integrated energy. Moving stimuli at threshold detectability are seen faster than non-moving threshold stimuli. Under some conditions the speed advantage is over 0.25 seconds. Similar advantages have also been shown to occur for suprathreshold signals.

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