scholarly journals Examining the Time Course of Ultra-Rapid Visual Categorization with Backward Masking

2004 ◽  
Vol 4 (8) ◽  
pp. 880-880
Author(s):  
J. L. Solberg ◽  
J. M. Brown
Keyword(s):  
Time Course ◽  
Backward Masking ◽  
Visual Categorization

The Temporal Course of Visual Pattern Encoding: Effects of Pattern Goodness

1983 ◽  
Vol 35 (4) ◽  
pp. 607-633 ◽  
Author(s):  
Edmund S. Howe ◽  
Cynthia J. Brandau
Keyword(s):  
Processing Time ◽  
Time Course ◽  
Short Term Memory ◽  
Experimental Situation ◽  
Stimulus Display ◽  
Backward Masking ◽  
Display Time ◽  
Pattern Goodness ◽  
Temporal Course ◽  
Encoding Effects

Subjects typically display superior reproduction of good (redundant, symmetrical) visual patterns compared with poor ones. This pattern goodness effect could conceivably involve encoding processes, short-term memory processes, or response processes. The present experiments explored the time course of wholistic encoding of Garner dot patterns as a function of tachistoscopic exposure time, delay of backward masking, and post-mask shadowing. Within the specific framework of additive factors theory, Experiment I showed: (a) equal rates of encoding for all patterns since comparable slopes were obtained for the recall X processing time functions; and (b) superior absolute recall for good patterns since different intercepts were obtained. Experiment II demonstrated that when degree of encoding was initially equalized for all patterns, the rate of extraction of further information remained constant over available processing time and was unaffected by pattern goodness, slopes and intercepts for good versus poor patterns then being equal. Experiment III confirmed that, given some fixed duration of available processing time, information is abstracted at the same rate for all pattern regardless of the ratio stimulus display time to delay of mask onset. Experiment IV indicated that maintenance rehearsal normally occurs in the present experimental situation, and that very good patterns are somewhat less disrupted by shadowing over a three-second interval. While STM is thus implicated in the pattern goodness effect it does not follow that STM constitutes a complete explanation of the intercept differences reported here. Empirical evidence of response bias toward production of good patterns, however, was not found. It was shown that very good patterns are highly familiar and nameable, and proposed that they do consequently have an early encoding advantage.

Differential Controls Over Tactile Detection in Humans by Motor Commands and Peripheral Reafference

2006 ◽  
Vol 96 (3) ◽  
pp. 1664-1675 ◽  
Author(s):  
C. Elaine Chapman ◽  
Evelyne Beauchamp
Keyword(s):  
Time Course ◽  
Index Finger ◽  
Motor Command ◽  
Electromyographic Activity ◽  
Backward Masking ◽  
Motor Tasks ◽  
Motor Commands ◽  
Tactile Stimuli ◽  
Tactile Detection ◽  
Electrical Stimuli

The purpose of this study was to determine the extent to which motor commands and peripheral reafference differentially control the detection of near-threshold, tactile stimuli. Detection of weak electrical stimuli applied to the index finger (D2) was evaluated with two bias-free measures of sensory detection, the index of detectability ( d′) and the proportion of stimuli detected. Stimuli were presented at different delays prior to and during two motor tasks, D2 abduction, and elbow extension; both tasks were tested in two modes, active and passive. For both active tasks, the peak decrease in tactile suppression occurred at the onset of electromyographic activity. The time course for the suppression of detection during active and passive D2 abduction was identical, and preceded the onset of movement (respectively, −35 and −47 ms). These results suggest that movement reafference alone, acting through a mechanism of backward masking, could explain the modulation seen with D2 movement. In contrast, tactile suppression was significantly earlier for active elbow movements (−59 ms) as compared with passive (−21 ms), an observation consistent with both the motor command and peripheral reafference contributing to the suppression of detection of stimuli applied to D2 during movements about a proximal joint. A role for the motor command in tactile gating during distal movements cannot be discounted, however, because differences in the strength and distribution of the peripheral reafference may also have contributed to the proximo-distal differences in the timing of the suppression.

scholarly journals Saccadic suppression in schizophrenia

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rebekka Lencer ◽  
Inga Meyhöfer ◽  
Janina Triebsch ◽  
Karen Rolfes ◽  
Markus Lappe ◽  
...  
Keyword(s):  
Time Course ◽  
Visual Disturbance ◽  
Efference Copy ◽  
Visual Sensitivity ◽  
Saccadic Suppression ◽  
Backward Masking ◽  
Control Task ◽  
Saccade Onset ◽  
Saccade Control ◽  
Visual Disturbances

AbstractAbout 40% of schizophrenia patients report discrete visual disturbances which could occur if saccadic suppression, the decrease of visual sensitivity around saccade onset, is impaired. Two mechanisms contribute to saccadic suppression: efference copy processing and backwards masking. Both are reportedly altered in schizophrenia. However, saccadic suppression has not been investigated in schizophrenia. 17 schizophrenia patients and 18 healthy controls performed a saccadic suppression task using a Gabor stimulus with individually adjusted contrast, which was presented within an interval 300 ms around saccade onset. Visual disturbance scores were higher in patients than controls, but saccadic suppression strength and time course were similar in both groups with lower saccadic suppression rates being similarly related to smaller saccade amplitudes. Saccade amplitudes in the saccadic suppression task were reduced in patients, in contrast to unaltered amplitudes during a saccade control task. Notably, smaller saccade amplitudes were related to higher visual disturbances scores in patients. Saccadic suppression performance was unrelated to symptom expression and antipsychotic medication. Unaltered saccadic suppression in patients suggests sufficiently intact efference copy processing and backward masking as required for this task. Instead, visual disturbances in patients may be related to restricted saccadic amplitudes arising from cognitive load while completing a task.

The time course of visual categorization: Electrophysiological evidence from ERP

2006 ◽  
Vol 51 (13) ◽  
pp. 1586-1592 ◽  
Author(s):  
Antao Chen ◽  
Hong Li ◽  
Jiang Qiu ◽  
Yuejia Luo
Keyword(s):  
Time Course ◽  
Visual Categorization ◽  
Electrophysiological Evidence

scholarly journals The time course of visual processing: Backward masking and natural scene categorisation

2005 ◽  
Vol 45 (11) ◽  
pp. 1459-1469 ◽  
Author(s):  
Nadège Bacon-Macé ◽  
Marc J.-M. Macé ◽  
Michèle Fabre-Thorpe ◽  
Simon J. Thorpe
Keyword(s):  
Visual Processing ◽  
Time Course ◽  
Backward Masking ◽  
Natural Scene

Learning selective top-down control enhances performance in a visual categorization task

2012 ◽  
Vol 108 (11) ◽  
pp. 3124-3137 ◽  
Author(s):  
Mario Pannunzi ◽  
Guido Gigante ◽  
Maurizio Mattia ◽  
Gustavo Deco ◽  
Stefano Fusi ◽  
...  
Keyword(s):  
Time Course ◽  
Signal To Noise Ratio ◽  
Temporal Cortex ◽  
Inferior Temporal Cortex ◽  
Feedback Signal ◽  
Top Down ◽  
Categorization Task ◽  
Tuning Curves ◽  
Visual Categorization ◽  
Neural Activities

We model the putative neuronal and synaptic mechanisms involved in learning a visual categorization task, taking inspiration from single-cell recordings in inferior temporal cortex (ITC). Our working hypothesis is that learning the categorization task involves both bottom-up, ITC to prefrontal cortex (PFC), and top-down (PFC to ITC) synaptic plasticity and that the latter enhances the selectivity of the ITC neurons encoding the task-relevant features of the stimuli, thereby improving the signal-to-noise ratio. We test this hypothesis by modeling both areas and their connections with spiking neurons and plastic synapses, ITC acting as a feature-selective layer and PFC as a category coding layer. This minimal model gives interesting clues as to properties and function of the selective feedback signal from PFC to ITC that help solving a categorization task. In particular, we show that, when the stimuli are very noisy because of a large number of nonrelevant features, the feedback structure helps getting better categorization performance and decreasing the reaction time. It also affects the speed and stability of the learning process and sharpens tuning curves of ITC neurons. Furthermore, the model predicts a modulation of neural activities during error trials, by which the differential selectivity of ITC neurons to task-relevant and task-irrelevant features diminishes or is even reversed, and modulations in the time course of neural activities that appear when, after learning, corrupted versions of the stimuli are input to the network.

Investigating the Time-Course of Task-Dependent Perceptual Grouping

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 148-148
Author(s):  
E D Freeman
Keyword(s):  
Perceptual Grouping ◽  
Time Course ◽  
Shape Matching ◽  
Early Stage ◽  
Backward Masking ◽  
Task Context ◽  
Visual Processes ◽  
Task Experience ◽  
Selection Of ◽  
And Task

At what stage do factors such as task experience and expectation interact with the perception of whole objects? Recent work (Freeman, 1995 Perception24 Supplement, 134; 1996 Perception25 Supplement, 51) suggests that perceptual grouping of ambiguous 1-Whole/2-Wholes stimuli is dependent upon learning and task predictability, as inferred from changes in performance in a Whole - Whole/Whole - Part shape matching paradigm. Thus, subjects seemed able to offset the effect of a stimulus parameter known to influence perceived grouping, in order to see the grouping they had been trained to see or were expecting to see. In the present research the timing of these interactive processes was investigated, with the use of backward masking to take a snapshot of visual processes at different stages in their development. Stimulus and task-context factors were found to interact even at the shortest masking interval (50 ms), suggesting that top - down knowledge constrains perceptual grouping processes from an early stage onwards. A simple model of the development of 1-Whole and 2-Whole percepts implies two further conclusions. First, task and stimulus factors both seem to work by modifying the rate of development of the alternative percepts. Second, and counter-intuitively, it appears that, given the appropriate task-context and stimuli, it is possible to group the stimulus in several different ways at once. These results shed light on issues concerning the nature of perceptual grouping, and the process by which our experience of objects is brought to bear on our selection of functional perceptual groups.

What Is Shaping RT and Accuracy Distributions? Active and Selective Response Inhibition Causes the Negative Compatibility Effect

2016 ◽  
Vol 28 (11) ◽  
pp. 1651-1671 ◽  
Author(s):  
Sven Panis ◽  
Thomas Schmidt
Keyword(s):  
Response Inhibition ◽  
Compatibility Effect ◽  
Time Course ◽  
Selective Inhibition ◽  
Masked Priming ◽  
Backward Masking ◽  
Hazard Functions ◽  
Negative Compatibility Effect ◽  
Priming Paradigm ◽  
Prime Target

Inhibitory control such as active selective response inhibition is currently a major topic in cognitive neuroscience. Here we analyze the shape of behavioral RT and accuracy distributions in a visual masked priming paradigm. We employ discrete time hazard functions of response occurrence and conditional accuracy functions to study what causes the negative compatibility effect (NCE)—faster responses and less errors in inconsistent than in consistent prime target conditions—during the time course of a trial. Experiment 1 compares different mask types to find out whether response-relevant mask features are necessary for the NCE. After ruling out this explanation, Experiment 2 manipulates prime mask and mask target intervals to find out whether the NCE is time-locked to the prime or to the mask. We find that (a) response conflicts in inconsistent prime target conditions are locked to target onset, (b) positive priming effects are locked to prime onset whereas the NCE is locked to mask onset, (c) active response inhibition is selective for the primed response, and (d) the type of mask has only modulating effects. We conclude that the NCE is neither caused by automatic self-inhibition of the primed response due to backward masking nor by updating response-relevant features of the mask, but by active mask-triggered selective inhibition of the primed response. We discuss our results in light of a recent computational model of the role of the BG in response gating and executive control.

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