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Substantial evidence supports the hypothesis that visual detection in the presence of masking noise occurs at a constant signal/noise ratio only if the subject is unfamiliar with the mask. A variety of studies of the proposed sustained/transient mechanism model have failed to find support for a dichotomous visual system, and have failed to replicate some of the classical studies in this area. Studies of hypothetical velocity-tuned channels suggest the possible existence of such channels, but show that they are, at best, mixed in their tuning properties. Weisstein'g Pixel Flicker technique has been found to be an artifact of an unrealistic algorithm for adding noise to a visual scene. Other temporal enhancement schemes show some promise.

Project Title: The effect of visual field and transliminality score on common onset masking. Project Investigators: Steven J. Haase, Ph.D; Gary D. Fisk, Ph.D Project goals: The goal of the research is multifaceted, from looking at basic instrumentation and software performance of conducting perception experiments online (using PsyToolkit), to further investigating the joint influences of congruency and masking on simple shape identification. In addition, this exploratory study will investigate whether there are performance differences based on which visual field the display is presented to (left vs. right), and also whether there are individual differences based on one’s cognitive threshold (i.e., transliminality). Background: Common onset masking (COM) was first reported in a paper by DiLollo, Bischof, and Dixon (1993). This type of masking is similar to metacontrast, in that the masks and target do not overlap spatially. However, the difference is that common onset masking has its influence when there is more spatial separation between the target and mask—and in some cases the masking can occur with very sparse stimuli, such as four small dots. Our interest in this paradigm stems from prior exploratory work where we compared different forms of masking (pattern, metacontrast) along with temporal crowding. In addition, a congruency factor was included. There were two simple shapes (diamond, square) that could be masked or crowded with the same or different shapes. Congruency experiments are an important method for studying visual information processing (Schmidt, Haberkamp, & Schmidt, 2011). We obtained a small amount of foveal crowding in a condition that involved more spatial separation than typical metacontrast experiments. Investigating the influence of COM in a similar situation is a natural outgrowth of this research endeavor. Design: The experiment involves the following independent variables in a 2 x 2 within participants design: 1) Congruency (the target shape is the same as the masking shapes or different from the masking shapes). Two simple shapes are used—a horizontal and vertical rectangle 2) Visual field (displays are presented to the left or right of fixation (position above or below the fixation is also coded, so, subsequently, a separate analysis could be conducted on this position difference as well, collapsed across left/right—there is some evidence that visual shape information is better processed in the lower portion of the visual field—Zito et al. (2016)). Measures: We are collecting the following demographic information: Age, gender, handedness. We are collecting responses on the revised transliminality scale (Lange, Thalbourne, Houran, & Storm, 2000). We will measure response time for target identification and accuracy in target identification. Procedure: a. Initial pilot work (approximate n = 20). 1. Participants will click on a link to begin the study. 2. The first part will involve electronic informed consent. 3. Once participants provide informed consent, they will be asked to answer a number of demographic questions and then answer 17 questions that attempt to measure cognitive thresholds, via the “transliminality” scale (for information, see: https://www.researchgate.net/publication/12179666_The_Revised_Transliminality_Scale_Reliability_and_Validity_Data_From_a_Rasch_Top-Down_Purification_Procedure ). 4. Following completion of the survey, participants will complete a common onset masking perceptual task. The task will begin with instructions, 16 practice trials (with a longer target duration of 256 ms), then three sets of experimental trials (with 40 trials per set). The program manipulates the target shape (horizontal or vertical rectancle) on each trial and also the background shapes (horizontal or vertical rectangles that surround the target). The location of the target and background (masking) shapes is also varied from trial to trial in one of four positions around a fixation point. Following a 500 ms central fixation cross, Targets + Masks are displayed for 128 ms and trailing Masks for 500 ms. Participants have up to 3 s to make an identification response using the ‘c’ key for horizontal rectangle and ‘m’ key for vertical rectangle. There is a 1 s inter-trial interval. Feedback is provided on both practice and experimental trials. At the end, participants are asked to estimate their performance accuracy and then they are given information about the study (debriefing). The entire task takes approximately 15 minutes. 5. The link to the survey and experiment is here: https://www.psytoolkit.org/c/3.2.0/survey?s=Qa2Y2 b. Further studies will be based upon the results of the pilot work. There may need to be changes in stimulus timing, feedback, and/or other parameters, should the results be too variable or unclear to show reasonable effect sizes. If the results are closely in line with our predictions below, we will replicate the study with a separate sample of 20 participants. Hypotheses: 1. We predict a strong congruency effect with congruent trials being faster and more accurate than incongruent trials. Some of this effect may be due to response bias, in participants selecting the mask shapes for their response, since the target is difficult perceive. This may occur even though participants are informed that there will be an equal number of target and mask shapes and the shape for each is randomized across trials. The main effect of congruency is a highly expected (though not novel) finding. 2. We also predict that displays on the left of center will be faster and more accurate than displays on the right. While this effect may be somewhat small, it is based on the hypothesis that visual shape information is processed more quickly in the right compared to the left hemisphere (Verleger et al., 2010). This effect could also be due to the left-right reading bias in English. 3. In addition, there is research to support better processing for visual object information at the top of the display compared to the bottom part of the display (where motion perception shows an advantage). We can test for this as well, as half of the displays are presented below the fixation point. This hypothesis is more exploratory and subsidiary to #2 but there is some evidence to support it based on Zito et al. In fact, our displays combine movement in the process of COM. 4. Our investigation into transliminality is somewhat more exploratory, but there may be some connection with participants with higher scores on this scale having better perception of fleeting visual information. Sample size: Typically, we have found that a sample size of 20-25 is sufficient to explore hypothesis testing with adequate power. If effects are weak and or significant, the study will be reconceptualized. There are number of different options that can be modified such as the stimuli (we have done pilot work using letters), and the target duration (which is relatively long in this study (128 ms), compared to most COM studies (33-66ms), likely due to the movement in the display of target + masks in the near periphery to the trailing masks display appearing in the center.. References: Di Lollo, V., Bischof, W. F., & Dixon, P. (1993). Stimulus-onset asynchrony is not necessary for motion perception or metacontrast masking. Psychological Science, 4, 260–263. https://doi.org/10.1111/j.1467-9280.1993.tb00272.x Lange, R., Thalbourne, M. A., Houran, J., & Storm, L. (2000). The revised Transliminality Scale: Reliability and validity data from a Rasch top-down purification procedure. Consciousness and Cognition: An International Journal, 9(4), 591–617. https://doi.org/10.1006/ccog.2000.0472 Schmidt, F., Haberkamp, A., & Schmidt, T. (2011). Dos and don’ts in response priming research. Advances in Cognitive Psychology, 7(2), 120–131. https://doi.org/10.2478/v10053-008-0092-2 Verleger, R., Möller, F., Kuniecki, M., Śmigasiewicz, K., Groppa, S., & Siebner, H. R. (2010). The left visual-field advantage in rapid visual presentation is amplified rather than reduced by posterior-parietal rTMS. Experimental Brain Research, 203(2), 355–365. https://doi.org/10.1007/s00221-010-2237-z Zito, G. A., Cazzoli, D., Müri, R. M., Mosimann, U. P., & Nef, T. (2016). Behavioral differences in the upper and lower visual hemifields in shape and motion perception. Frontiers in Behavioral Neuroscience, 10. doi: 10.3389/fnbeh.2016.00128

Several previous research on visual consciousness has shown that when a stimulus is presented for a sufficient time to be processed, we can perceive it consciously. Specifically, consciousness has an all-or-nothing, sigmoidal emergent process between pre-threshold and post-threshold. However, the development of visual consciousness, indexed by the threshold and the emergent processes, are still unknown. We will examine what the subjective and objective thresholds and emergent processes of visual consciousness are in young children and adults. Five-to-6-year-old children and adults will participate in this study. In our experiment, children and adults were given a visual awareness task using a square or a diamond as the target stimulus. Four conditions of stimulus onset asynchronies (SOAs) were randomly intermixed across trials (40, 80, 120, and 160 ms). We measured the accuracy rate (A square or a diamond?) and the Perceptual Awareness Scale rate (How clear did you see it?). After the non-linear models (Sandberg et al., 2011) were fitted to the accuracy and PAS rate, we compared the parameters such as the threshold and the steepness of the models in young children and adults.

Studies continue on spatio-temporal interactions between briefly-flashed lines. The delayed facilitation we previously reported suggested that we were tapping a motion-detector system. However extensive experiments which failed to correlate our line interactions with the motion aftereffect and other well-known manifestations of motion detection have convinced us that we are measuring something different. We currently believe we may be tapping the moving-object detectors described by Burr. We have demonstrated that transient stimulation produces a substantial change in the configuration of inhibition and excitation, as revealed by summation between briefly-flashed lines. We have extended our studies of summation between lines to parafoveal vision. Unlike most visual functions, spatial summation in the periphery does not increase in direct proportion to cortical magnification. Based on our studies of summation, we predicted and observed that aliasing, though absent in the fovea, should be present in the parafovea. Studies of velocity discrimination suggest that there do not exist a small numer of discrete velocity detectors, but rather a near-continuum of theses. Keywords: Visual targets; Moving targets; Visual perception.

Studies continue on spatio-temporal interactions between briefly-flashed lines. The delayed facilitation we previously reported suggested that we were tapping a motion-detector system. However extensive experiments which failed to correlate our line interactions with the motion aftereffect and other well-known manifestations of motion detection have convinced us that we are measuring something different. We currently believe we may be tapping the moving-object detectors described by Burr. We have demonstrated that transient stimulation produces a substantial change in the configuration of inhibition and excitation, as revealed by summation between briefly-flashed lines. We have extended our studies of summation between lines to parafoveal vision. Unlike most visual functions, spatial summation in the periphery does not increase in direct proportion to cortical magnification. Based on our studies of summation, we predicted and observed that aliasing, though absent in the fovea, should be present in the parafovea. Studies of velocity discrimination suggest that there do not exist a small numer of discrete velocity detectors, but rather a near-continuum of theses. Keywords: Visual targets; Moving targets; Visual perception.

Studies continue on spatio-temporal interactions between briefly-flashed lines. The delayed facilitation we previously reported suggested that we were tapping a motion-detector system. However extensive experiments which failed to correlate our line interactions with the motion aftereffect and other well-known manifestations of motion detection have convinced us that we are measuring something different. We currently believe we may be tapping the moving-object detectors described by Burr. We have demonstrated that transient stimulation produces a substantial change in the configuration of inhibition and excitation, as revealed by summation between briefly-flashed lines. We have extended our studies of summation between lines to parafoveal vision. Unlike most visual functions, spatial summation in the periphery does not increase in direct proportion to cortical magnification. Based on our studies of summation, we predicted and observed that aliasing, though absent in the fovea, should be present in the parafovea. Studies of velocity discrimination suggest that there do not exist a small numer of discrete velocity detectors, but rather a near-continuum of theses. Keywords: Visual targets; Moving targets; Visual perception.

Previous research has suggested that images initially presented with coincidental, semantically congruent sounds are more accurately recognized later than images that are initially presented unimodally, with an incongruent sound, or with a nonsensical sound (Lehmann and Murray, 2005; see Matusz, Wallace, and Murray, 2017 for a review). The goal of the present study is to conceptually replicate results from the second experiment conducted by Lehmann and Murray (2005) using 3-dimensional object images, a completely audiovisual encoding phase, a more specific source memory task, and a blocked design with separate audiovisual encoding and visual recognition phases.

Previous research has suggested that images initially presented with coincidental, semantically congruent sounds are more accurately recognized later than images that are initially presented unimodally, with an incongruent sound, or with a nonsensical sound (Lehmann and Murray, 2005; see Matusz, Wallace, and Murray, 2017 for a review). The goal of the present study is to conceptually replicate results from the second experiment conducted by Lehmann and Murray (2005) using 3-dimensional object images, a completely audiovisual encoding phase, a more specific source memory task, and a blocked design with separate audiovisual encoding and visual recognition phases.

This article is from PLoS ONE , volume 9 . Abstract Object-substitution masking (OSM) occurs when a briefly presented target in a search array is surrounded by small dots that remain visible after the target disappears. The reduction of target visibility occurring after OSM has been suggested to result from a specific interference with reentrant visual processing while the initial feedforward processing is thought to be left intact. We tested a prediction derived from this hypothesis: the fastest responses, being triggered before the beginning of reentrant processing, should escape the OSM interference. In a saccadic choice reaction time task, which gives access to very early stages of visual processing, target visibility was reduced either by OSM, conventional backward masking, or low stimulus contrast. A general reduction of performance was observed in all three conditions. However, the fastest saccades did not show any sign of interference under either OSM or backward masking, as they did under the low-contrast condition. This finding supports the hypothesis that masking interferes mostly with reentrant processing at later stages, while leaving early feedforward processing largely intact.

Since eye movements are required for the detection and tracking of a point target, their concomitant signal can provide physiological objective measures of performance in target acquisition tasks. Saccadic latency, misses, and false alarm rate were used in assessing and comparing the effects of static and dynamic masks on target detection and tracking. A point target with an effective diameter of 0.4 degrees was displayed in either of two fixed positions separated by 18 degrees symmetrically with respect to the egocentric axis. Timing of target displacement was either periodic, or aperiodic. The masking field was generated by projection of a polarized texture pattern, characterized by a spectrum below 1 cpd, superimposed on the visual axis via a beam splitter. Masking dynamics were generated by a rotating polarizer situated in front of the masking field projector. As target luminance decreased from 11 to 6 ft-L, reaction time measured as saccadic latency, increased. This effect of target luminance was further substantiated once static masking was introduced. Aperiodic target displacements resulted in false alarm saccades to the right position. It was found that dynamic mask of the same spatial spectrum and contrast had a significantly more detrimental effect on subject performance.

This article is from BMC Neuroscience , volume 15 . Abstract None

This article is from Frontiers in Human Neuroscience , volume 8 . Abstract It is generally supposed that there is a single, hierarchically organized pathway dedicated to form processing, in which complex forms are elaborated from simpler ones, beginning with the orientation-selective cells of V1. In this psychophysical study, we undertook to test another hypothesis, namely that the brain’s visual form system consists of multiple parallel systems and that complex forms are other than the sum of their parts. Inspired by imaging experiments which show that forms of increasing perceptual complexity (lines, angles, and rhombuses) constituted from the same elements (lines) activate the same visual areas (V1, V2, and V3) with the same intensity and latency (Shigihara and Zeki, 2013, 2014), we used backward masking to test the supposition that these forms are processed in parallel. We presented subjects with lines, angles, and rhombuses as different target-mask pairs. Evidence in favor of our supposition would be if masking is the most effective when target and mask are processed by the same system and least effective when they are processed in different systems. Our results showed that rhombuses were strongly masked by rhombuses but only weakly masked by lines or angles, but angles and lines were well masked by each other. The relative resistance of rhombuses to masking by low-level forms like lines and angles suggests that complex forms like rhombuses may be processed in a separate parallel system, whereas lines and angles are processed in the same one.

The present study examined the effects of low-intensity laser glue, far below a level that would cause ocular damage or flashblindness, on the visually guided performance of aviators. With a forward-masking paradigm, this study showed that the time at which laser glare is experienced, relative to initial acquisition of visual information, differentially affects the speed and accuracy of target-location performance. Brief exposure (300 ms) to laser glare, terminating with a visual scene's onset, produced significant decrements in target-location performance relative to a no-glare control whereas a 150 and 300-ms delay of display onset (DDO) had very little effect. The intensity of the light entering the eye and producing these effects was far below the Maximum Permissible Exposure (MPE) limit for safe viewing of coherent light produced by an argon laser. In addition, these effects were modulated by the distance of the target from the center of the visual display. This study demonstrated that the presence of laser glare is not sufficient, in and of itself, to diminish target- location performance. The time at which laser glare is experienced is an important factor in determining the probability and extent of visually mediated performance decrements.

Two major studies have been completed this year, and several others are in progress. In visual masking, we have studied the effect of different detection criteria and find that criterion has a more profound effect than is usually believed. Not only does criterion change alter overall sensitivity, but the qualitative nature may yield either Weber's Law behavior or power-law behavior, depending on criterion. We conclude that much of the literature on spatial frequency masking is essentially unrepliciable, since criterion was uncontrolled, and we offer possibility of using motion to enhance the visibility of displayed images, we have been studying hypothetical detectors for moving objects. We began this study with the simpliest possible stimulus, a pair of briefly-flashed lines, separated in space and time (a variant of the apparent motion paradigm). Although lateral interactions between line segments have generally been reported to be inhibitory, with this paradigm, we find a range of excitatory interactions which suggest a motion detector with a tuned velocity of about 3 deg/sec. Additional keywords: Vision, Visibility, Charts.

The research completed over the last twelve months has included a number of studies concerned with evoked cortical potential correlates of visual stimulus processing in humans. The first experiment was conducted in order to replicate an earlier finding in which the amplitude of a relatively late positive component of the event related potential (ERP), known as the P3, was larger to a line orientation that required a 'yes' response than one that required a 'no'. The angular difference between the two lines was only 5 degrees. Another purpose was to assess the reliability of the better right hemisphere performance found with male subjects in the line orientation discrimination task used. In a second experiment, we examined the possibility of hemispheric asymmetry in response to two different colors (red and blue). The two hemispheres responded in essentially the same manner to the two colors. However, an interesting finding was the larger ERPs of both left and right hemispheres to the color blue, especially with central visual field stimulation. A third experiment was directed at the determination of whether the right hemisphere would be more sensitive to visual masking than the left, especially with a metacontrast paradigm which is dependent on spatial factors to produce the masking effect. A fourth experiment was performed to determine the relative responsivity of the two hemispheres to verbal (letter) and spatial (geometric form) stimuli.

Virtually all research on inhibitory interactions among adjacent visual stimuli operative in such phenomena as simultaneous contrast and visual masking has employed situations in which the interacting stimulus elements occupy the same depth plane (i.e., have the same z-axis values) in deference to the implicit assumption that the processing of depth information occurs only after the visual processing of contour information is completed. But there are theoretical reasons and data suggesting that the interactions among contours depends critically upon their relative positions in depth--interactions may not occur if the stimulus elements occupy different depth positions. The extent to which metacontrast masking depends upon depth position was investigated in nine experiments that used stereoscopic contours formed from random-element stereograms as test and mask stimuli. The stereogram generation system permits large variations in depth to be made without introducing confounding changes in proximal stimulation. The main results are: (1) Separation of test and mask stimuli in depth substantially reduces masking; and (2) When more than one stimulus is in visual space; the stimulus that either appears first or appears closer to the observer receives preferential processing by the visual system. (Author)

Virtually all research on inhibitory interactions among adjacent visual stimuli operative in such phenomena as simultaneous contrast and visual masking has employed situations in which the interacting stimulus elements occupy the same depth plane (i.e., have the same z-axis values) in deference to the implicit assumption that the processing of depth information occurs only after the visual processing of contour information is completed. But there are theoretical reasons and data suggesting that the interactions among contours depends critically upon their relative positions in depth--interactions may not occur if the stimulus elements occupy different depth positions. The extent to which metacontrast masking depends upon depth position was investigated in nine experiments that used stereoscopic contours formed from random-element stereograms as test and mask stimuli. The stereogram generation system permits large variations in depth to be made without introducing confounding changes in proximal stimulation. The main results are: (1) Separation of test and mask stimuli in depth substantially reduces masking; and (2) When more than one stimulus is in visual space; the stimulus that either appears first or appears closer to the observer receives preferential processing by the visual system. (Author)

Visual masking using various test stimulus patterns