scholarly journals Temporal attention selectively enhances target features

2021 ◽  
Author(s):  
Luis D. Ramirez ◽  
Joshua J Foster ◽  
Sam Ling
Keyword(s):  
Formal Model ◽  
External Noise ◽  
Signal Enhancement ◽  
Orientation Discrimination ◽  
Temporal Attention ◽  
Noise Levels ◽  
Stimulus Enhancement ◽  
Divisive Normalization ◽  
Perceptual Performance ◽  
Improved Performance

Here, we examined the computations by which temporal attention, the allocation of attention to a moment in time, improves perception, under a divisive normalization framework. Under this framework, attention can improve perception of a target signal in three ways: stimulus enhancement (increasing gain across all sensory channels), signal enhancement (selectively increasing gain in channels that encode the target stimulus), or external noise exclusion (reducing the gain in channels that encode irrelevant features). These mechanisms make diverging predictions when a target is embedded in varying levels of noise: stimulus enhancement improves performance only when noise is low, signal enhancement improves performance at all noise intensities, and external noise exclusion improves performance only when noise is high. To date, temporal attention studies have used noise-free displays. Therefore, it is unclear whether temporal attention acts via stimulus enhancement (amplifying both target features and noise) or signal enhancement (selectively amplifying target features) because both mechanisms predict improved performance in the absence of noise. To tease these mechanisms apart, we manipulated temporal attention using an auditory cue while parametrically varying external noise in a fine-orientation discrimination task. Temporal attention improved performance across all noise levels. Formal model comparisons revealed that this cueing effect was best accounted for by a combination of signal enhancement and stimulus enhancement, suggesting that temporal attention improves perceptual performance, in part, by selectively increasing gain for target features.

scholarly journals Online Transcranial Random Noise stimulation improves perception at high levels of visual white noise

2020 ◽  
Author(s):  
Michael D. Melnick ◽  
Woon Ju Park ◽  
Sholei Croom ◽  
Shuyi Chen ◽  
Lorella Batelli ◽  
...  
Keyword(s):  
White Noise ◽  
Task Performance ◽  
Visual Processing ◽  
Random Noise ◽  
External Noise ◽  
Orientation Discrimination ◽  
Perceptual Training ◽  
Transcranial Random Noise Stimulation ◽  
Perceptual Performance ◽  
Underlying Mechanisms

AbstractTranscranial random noise stimulation (tRNS), a relatively recent addition to the field of non-invasive, electrical brain stimulation, has been shown to improve perceptual and cognitive functions across a wide variety of tasks. However, the underlying mechanisms of visual improvements caused by tRNS remain unclear. To study this question, we employed a well-established, equivalent-noise approach, which measures perceptual performance at various levels of external noise and is formalized by the Perceptual Template Model (PTM). This approach has been used extensively to infer the underlying mechanisms behind changes in visual processing, including those from perceptual training, adaptation and attention. Here, we used tRNS during an orientation discrimination task in the presence of increasing quantities of external visual white noise and fit the PTM to gain insights into the effects of tRNS on visual processing. Our results show that tRNS improves visual processing when stimulation is applied during task performance, but only at high levels of external visual white noise—a signature of improved external noise filtering. There were no significant effects of tRNS on task performance after the stimulation period. Of interest, the reported effects of tRNS on visual processing mimic those previously reported for endogenous spatial attention, offering a potential area of investigation for future work.

scholarly journals Investigating the Effects of tDCS on Visual Orientation Discrimination Task Performance: “the Possible Influence of Placebo”

2019 ◽  
Vol 4 (3) ◽  
pp. 235-249
Author(s):  
A. Bin Dawood ◽  
A. Dickinson ◽  
A. Aytemur ◽  
C. Howarth ◽  
E. Milne ◽  
...  
Keyword(s):  
Placebo Effect ◽  
Discrimination Task ◽  
Low Cost ◽  
Cortical Inhibition ◽  
Orientation Discrimination ◽  
Visual Orientation ◽  
Non Invasive ◽  
Clear Link ◽  
Cortical Modulation ◽  
Improved Performance

Abstract The non-invasive neuromodulation technique tDCS offers the promise of a low-cost tool for both research and clinical applications in psychology, psychiatry, and neuroscience. However, findings regarding its efficacy are often equivocal. A key issue is that the clinical and cognitive applications studied are often complex and thus effects of tDCS are difficult to predict given its known effects on the basic underlying neurophysiology, namely alterations in cortical inhibition-excitation balance. As such, it may be beneficial to assess the effects of tDCS in tasks whose performance has a clear link to cortical inhibition-excitation balance such as the visual orientation discrimination task (ODT). In prior studies in our laboratory, no practice effects were found during 2 consecutive runs of the ODT, thus in the current investigation, to examine the effects of tDCS, subjects received 10 min of 2 mA occipital tDCS (sham, anode, cathode) between a first and second run of ODT. Surprisingly, subjects’ performance significantly improved in the second run of ODT compared to the first one regardless of the tDCS stimulation type they received (anodal, cathodal, or sham-tDCS). Possible causes for such an improvement could have been due to either a generic “placebo” effect of tDCS (as all subjects received some form of tDCS) or an increased delay period between the two runs of ODT of the current study compared to our previous work (10-min duration required to administer tDCS as opposed to ~ 2 min in previous studies as a “break”). As such, we tested these two possibilities with a subsequent experiment in which subjects received 2-min or 10-min delay between the 2 runs (with no tDCS) or 10 min of sham-tDCS. Only sham-tDCS resulted in improved performance thus these data add to a growing literature suggesting that tDCS has powerful placebo effect that may occur even in the absence of active cortical modulation.

scholarly journals Endogenous cueing effects for detection can be accounted for by a decision model of selective attention

2020 ◽  
Vol 27 (2) ◽  
pp. 315-321
Author(s):  
Miranda L. Johnson ◽  
John Palmer ◽  
Cathleen M. Moore ◽  
Geoffrey M. Boynton
Keyword(s):  
Selective Attention ◽  
Decision Model ◽  
External Noise ◽  
Orientation Discrimination ◽  
Spatial Cues ◽  
Selective Perception ◽  
Sequential Condition ◽  
Cueing Effect ◽  
Temporal Intervals ◽  
Spatial Locations

AbstractSpatial cues help participants detect a visual target when it appears at the cued location. One hypothesis for this cueing effect, called selective perception, is that cueing a location enhances perceptual encoding at that location. Another hypothesis, called selective decision, is that the cue has no effect on perception, but instead provides prior information that facilitates decision-making. We distinguished these hypotheses by comparing a simultaneous display with two spatial locations to sequential displays with two temporal intervals. The simultaneous condition had a partially valid spatial cue, and the sequential condition had a partially valid temporal cue. Selective perception predicts no cueing effect for sequential displays given there is enough time to switch attention. In contrast, selective decision predicts cueing effects for sequential displays regardless of time. We used endogenous cueing of a detection-like coarse orientation discrimination task with clear displays (no external noise or postmasks). Results showed cueing effects for the sequential condition, supporting a decision account of selective attention for endogenous cueing of detection-like tasks.

Signal enhancement in the presence of high noise levels—the electrocardiogram

1996 ◽  
Vol 34 (7) ◽  
pp. 418-419 ◽  
Author(s):  
Corissa Thompson ◽  
Arne Troelstra
Keyword(s):  
Signal Enhancement ◽  
Noise Levels ◽  
High Noise

The Role of Target Salience in Crowding

Perception ◽  
10.1068/p5206 ◽  
2005 ◽  
Vol 34 (7) ◽  
pp. 823-833 ◽  
Author(s):  
Fatima M Felisberti ◽  
Joshua A Solomon ◽  
Michael J Morgan
Keyword(s):  
Individual Differences ◽  
Spatial Separation ◽  
Orientation Discrimination ◽  
Crowding Effect ◽  
Improved Performance

We studied ‘crowding’ in the parafovea using orientation identification of a Gabor target as the task, and flanking Gabors on an isoeccentric circle as distractors. Orientation-discrimination thresholds were raised by nearby flanking distractors. This crowding effect was increased by the number of distractors and decreased by the spatial separation between target and distractors. Crowding was greatest when the target was in the centre of the distractor array and smallest when the target was on the edge of the array. A cue indicating the position of the target improved performance when the position was otherwise unknown and the spatial separation between target and distractors was large, but the cue had no significant effect when separation was small. Increasing the contrast of the target relative to the distractors reduced crowding, but targets of smaller contrast than that of the distractors are even harder to identify than those of the same contrast. Putting the target and distractors in different depth planes decreased crowding for some observers, but there were qualitative individual differences. A large (say, 45°) difference in orientation between target and distractors caused the target to ‘pop out’ in a presence/absence task, despite the evidence from other studies that crowding is still found in these conditions. We conclude that salience has, at best, modest effects on crowding.

scholarly journals Accelerating Reinforcement Learning through Implicit Imitation

2003 ◽  
Vol 19 ◽  
pp. 569-629 ◽  
Author(s):  
B. Price ◽  
C. Boutilier
Keyword(s):  
Reinforcement Learning ◽  
State Space ◽  
Formal Model ◽  
The State ◽  
Learning Agent ◽  
Relative Value ◽  
Multiagent Environments ◽  
Improved Performance ◽  
Prioritized Sweeping ◽  
Extract Information

Imitation can be viewed as a means of enhancing learning in multiagent environments. It augments an agent's ability to learn useful behaviors by making intelligent use of the knowledge implicit in behaviors demonstrated by cooperative teachers or other more experienced agents. We propose and study a formal model of implicit imitation that can accelerate reinforcement learning dramatically in certain cases. Roughly, by observing a mentor, a reinforcement-learning agent can extract information about its own capabilities in, and the relative value of, unvisited parts of the state space. We study two specific instantiations of this model, one in which the learning agent and the mentor have identical abilities, and one designed to deal with agents and mentors with different action sets. We illustrate the benefits of implicit imitation by integrating it with prioritized sweeping, and demonstrating improved performance and convergence through observation of single and multiple mentors. Though we make some stringent assumptions regarding observability and possible interactions, we briefly comment on extensions of the model that relax these restricitions.

scholarly journals Acoustical Evaluation of Six ‘Green’ Office Buildings

2008 ◽  
Vol 3 (4) ◽  
pp. 108-118 ◽  
Author(s):  
Murray Hodgson
Keyword(s):  
Speech Intelligibility ◽  
Sound Absorption ◽  
Internal Noise ◽  
External Noise ◽  
Office Buildings ◽  
Performance Criteria ◽  
Noise Levels ◽  
Noise Sources ◽  
Design Decisions ◽  
Speech Intelligibility Index

To explain the reactions of the building occupants to their acoustical environments, meetings with the designers, walk-through surveys, and detailed acoustical measurements were done. The objective was to determine how design decisions affect office acoustical environments, and how to improve the acoustical design of ‘green’ office buildings. Design-performance criteria were established. Measurements were made of noise level, reverberation time, speech-intelligibility index (SII), and noise isolation. Noise levels were atypically low in unoccupied buildings with no mechanical ventilation, but excessive in areas near external walls next to noisy external noise sources—especially with windows open for ventilation—and in occupied buildings. Reverberation times were excessive in areas with large volumes and insufficient sound absorption. Speech intelligibility was generally adequate, but speech privacy was inadequate in shared and open-office areas, and into private offices with the doors open for ventilation. Improvement of the acoustical design of ‘green’ buildings must include increasing the external-internal noise isolation and that between workplaces, and the use of adequate sound absorption to control reverberation and noise.

scholarly journals A Systematic Comparison of Perceptual Performance in Softness Discrimination with Different Fingers

2020 ◽  
Vol 82 (7) ◽  
pp. 3696-3709
Author(s):  
Aaron C. Zoeller ◽  
Knut Drewing
Keyword(s):  
Ring Finger ◽  
Middle Finger ◽  
Dominant Hand ◽  
Sensory Sensitivities ◽  
Motor Abilities ◽  
Soft Objects ◽  
Perceptual Performance ◽  
Improved Performance ◽  
Spontaneous Exploration ◽  
Little Finger

Abstract In studies investigating haptic softness perception, participants are typically instructed to explore soft objects by indenting them with their index finger. In contrast, performance with other fingers has rarely been investigated. We wondered which fingers are used in spontaneous exploration and if performance differences between fingers can explain spontaneous usage. In Experiment 1 participants discriminated the softness of two rubber stimuli with hardly any constraints on finger movements. Results indicate that humans use successive phases of different fingers and finger combinations during an exploration, preferring index, middle, and (to a lesser extent) ring finger. In Experiment 2 we compared discrimination thresholds between conditions, with participants using one of the four fingers of the dominant hand. Participants compared the softness of rubber stimuli in a two-interval forced choice discrimination task. Performance with index and middle finger was better as compared to ring and little finger, the little finger was the worst. In Experiment 3 we again compared discrimination thresholds, but participants were told to use constant peak force. Performance with the little finger was worst, whereas performance for the other fingers did not differ. We conclude that in spontaneous exploration the preference of combinations of index, middle, and partly ring finger seems to be well chosen, as indicated by improved performance with the spontaneously used fingers. Better performance seems to be based on both different motor abilities to produce force, mainly linked to using index and middle finger, and different sensory sensitivities, mainly linked to avoiding the little finger.

The neural basis for violations of Weber’s law in self-motion perception

2021 ◽  
Vol 118 (36) ◽  
pp. e2025061118
Author(s):  
Jerome Carriot ◽  
Kathleen E. Cullen ◽  
Maurice J. Chacron
Keyword(s):  
Discrimination Performance ◽  
Fundamental Principle ◽  
Weber’S Law ◽  
Neural Basis ◽  
Sensory Stimuli ◽  
Weber's Law ◽  
Perceptual Performance ◽  
Improved Performance ◽  
Self Motion ◽  
Neural Variability

A prevailing view is that Weber’s law constitutes a fundamental principle of perception. This widely accepted psychophysical law states that the minimal change in a given stimulus that can be perceived increases proportionally with amplitude and has been observed across systems and species in hundreds of studies. Importantly, however, Weber’s law is actually an oversimplification. Notably, there exist violations of Weber’s law that have been consistently observed across sensory modalities. Specifically, perceptual performance is better than that predicted from Weber’s law for the higher stimulus amplitudes commonly found in natural sensory stimuli. To date, the neural mechanisms mediating such violations of Weber’s law in the form of improved perceptual performance remain unknown. Here, we recorded from vestibular thalamocortical neurons in rhesus monkeys during self-motion stimulation. Strikingly, we found that neural discrimination thresholds initially increased but saturated for higher stimulus amplitudes, thereby causing the improved neural discrimination performance required to explain perception. Theory predicts that stimulus-dependent neural variability and/or response nonlinearities will determine discrimination threshold values. Using computational methods, we thus investigated the mechanisms mediating this improved performance. We found that the structure of neural variability, which initially increased but saturated for higher amplitudes, caused improved discrimination performance rather than response nonlinearities. Taken together, our results reveal the neural basis for violations of Weber’s law and further provide insight as to how variability contributes to the adaptive encoding of natural stimuli with continually varying statistics.

Comparative Analysis of EMD and VMD Algorithm in Speech Enhancement

2017 ◽  
Vol 6 (1) ◽  
pp. 17-35 ◽  
Author(s):  
Rashmirekha Ram ◽  
Mihir Narayan Mohanty
Keyword(s):  
Wiener Filter ◽  
Optimization Methods ◽  
Signal Enhancement ◽  
Signal Decomposition ◽  
Noise Levels ◽  
Result Section ◽  
Data Mining Approach ◽  
Mode Decomposition ◽  
Alternative Choice ◽  
Better Than

Signal enhancement is useful in many areas like social, medicine and engineering. It can be utilized in data mining approach for social and security aspects. Signal decomposition method is an alternative choice due to the elimination of noise and signal enhancement. In this paper, two different algorithms such as Empirical Mode Decomposition (EMD) and Variational Mode Decomposition (VMD) are used. The bands are updated concurrently and adaptively in each mode. That performs better than the traditional methods for non-recursive signals. Further it has been investigated that VMD outperforms EMD due to its self-optimization methods as well as adaptively using Wiener filter. It is shown in the result section. Different noise levels as 0dB, 5dB, 10dB and 15dB are considered for input signal.

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