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Journal of Vision Jul 2023To investigate the mechanisms underlying elongated spatial summation with a pattern-masking paradigm, we measured the contrast detection thresholds for elongated Gabor...
To investigate the mechanisms underlying elongated spatial summation with a pattern-masking paradigm, we measured the contrast detection thresholds for elongated Gabor targets situated at 3° eccentricity to either the left or right of the fixation and elongated along an arc of the same radius to access homogeneous retinal sensitivity. The mask was a ring with a Gabor envelope of the same 3° center radius containing either a concentric (iso-orientation mask) or a radial (orthogonal mask) modulation. The task of the observer was to indicate whether the target in each trial was on the left or the right of the fixation. With orthogonal or low contrast iso-orientation masks, target thresholds first decreased with size with slope -1 on log-log coordinates until the target length reached 45' (specified as the half-height full-width of the Gabor envelope) and then further decreased according to a slope of -1/2, the latter being the signature of an ideal summation process. When the contrast of the iso-orientation mask was sufficiently high, however, the target thresholds, while still showing a -1 slope up to ∼10', asymptoted up to about 50' length, suggesting that the presence of the mask eliminated the ideal summation regime. Beyond about 50', the data approximated another -1 slope decrease in threshold, suggesting the existence of an extra-long channel that is not revealed by the conventional spatial summation paradigm. The full results could be explained by a divisive inhibition model, in which second-order filters sum responses across local oriented channels, combined with a single extra-long filter at least 300' in extent. In this model, the local filter response is given by the linear excitation of the local channels raised to a power, and scaled by divisive inhibition from all channels in the neighborhood. With the high-contrast iso-orientation masks, such divisive inhibition swamps the response to eliminate the ideal summation regime until the stimulus is long enough to activate the extra-long filter.
Topics: Humans; Contrast Sensitivity; Sensory Thresholds; Perceptual Masking; Inhibition, Psychological
PubMed: 37505916
DOI: 10.1167/jov.23.7.17 -
Journal of Vision Apr 2024Perceptual confidence is thought to arise from metacognitive processes that evaluate the underlying perceptual decision evidence. We investigated whether metacognitive...
Perceptual confidence is thought to arise from metacognitive processes that evaluate the underlying perceptual decision evidence. We investigated whether metacognitive access to perceptual evidence is constrained by the hierarchical organization of visual cortex, where high-level representations tend to be more readily available for explicit scrutiny. We found that the ability of human observers to evaluate their confidence did depend on whether they performed a high-level or low-level task on the same stimuli, but was also affected by manipulations that occurred long after the perceptual decision. Confidence in low-level perceptual decisions degraded with more time between the decision and the response cue, especially when backward masking was present. Confidence in high-level tasks was immune to backward masking and benefitted from additional time. These results can be explained by a model assuming confidence heavily relies on postdecisional internal representations of visual stimuli that degrade over time, where high-level representations are more persistent.
Topics: Humans; Metacognition; Mental Processes; Decision Making
PubMed: 38558159
DOI: 10.1167/jov.24.4.2 -
The Journal of the Acoustical Society... Jul 2023Masking can reduce the efficiency of communication and prey and predator detection. Most underwater sounds fluctuate in amplitude, which may influence the amount of...
Masking can reduce the efficiency of communication and prey and predator detection. Most underwater sounds fluctuate in amplitude, which may influence the amount of masking experienced by marine mammals. The hearing thresholds of two harbor seals for tonal sweeps (centered at 4 and 32 kHz) masked by sinusoidal amplitude modulated (SAM) Gaussian one-third octave noise bands centered around the narrow-band test sweep frequencies, were studied with a psychoacoustic technique. Masking was assessed in relation to signal duration, (500, 1000, and 2000 ms) and masker level, at eight amplitude modulation rates (1-90 Hz). Masking release (MR) due to SAM compared thresholds in modulated and unmodulated maskers. Unmodulated maskers resulted in critical ratios of 21 dB at 4 kHz and 31 dB at 32 kHz. Masked thresholds were similarly affected by SAM rate with the lowest thresholds and the largest MR being observed for SAM rates of 1 and 2 Hz at higher masker levels. MR was higher for 32-kHz maskers than for 4-kHz maskers. Increasing signal duration from 500 ms to 2000 ms had minimal effect on MR. The results are discussed with respect to MR resulting from envelope variation and the impact of noise in the environment on target signal detection.
Topics: Animals; Auditory Threshold; Phoca; Perceptual Masking; Noise; Hearing; Cetacea
PubMed: 37409781
DOI: 10.1121/10.0019631 -
Scientific Reports Nov 2023Heterophoria is a common type of binocular fusion disorder that consists of a latent eye misalignment with potential consequences on daily activities such as reading or...
Heterophoria is a common type of binocular fusion disorder that consists of a latent eye misalignment with potential consequences on daily activities such as reading or working on a computer (with CVS). Crowding, a type of contextual modulation, can also impair reading. Our recent studies found an abnormal pattern of low-level visual processing with larger perceptive fields (PF) in heterophoria. The PF is the fundamental processing unit of human vision and both masking and crowding depend on its size. We investigated how heterophoria would impact the PF's size via a lateral masking experiment and consequently affect the foveal crowding at different letter-spacings (the crowding zone). More specifically, we explored the relationship between crowding, lateral masking, the PF's size, and the amount of heterophoria. The binocular horizontal PF's size was larger with heterophoric subjects, in agreement with our previous study. We found a stronger crowding and an extended crowding zone associated with slower response times; this shows that the processing of letter identification under both crowded and uncrowded conditions requires more processing effort in heterophoric individuals. In agreement with previous studies, we found a correlation between the crowding zone and the PF's size; each was strongly correlated with the amount of phoria. These findings resemble those involving the PF size and the extended crowding found at the fovea in amblyopia and young children. We suggest that these findings could help explain the inter-observers' variability found in the masking literature, and the reading difficulties often encountered in subjects with high heterophoria.
Topics: Child; Humans; Child, Preschool; Visual Acuity; Perceptual Masking; Visual Perception; Amblyopia; Strabismus; Malocclusion; Pattern Recognition, Visual
PubMed: 37935803
DOI: 10.1038/s41598-023-46291-w -
Nature Neuroscience Jan 2024Visual masking can reveal the timescale of perception, but the underlying circuit mechanisms are not understood. Here we describe a backward masking task in mice and...
Visual masking can reveal the timescale of perception, but the underlying circuit mechanisms are not understood. Here we describe a backward masking task in mice and humans in which the location of a stimulus is potently masked. Humans report reduced subjective visibility that tracks behavioral deficits. In mice, both masking and optogenetic silencing of visual cortex (V1) reduce performance over a similar timecourse but have distinct effects on response rates and accuracy. Activity in V1 is consistent with masked behavior when quantified over long, but not short, time windows. A dual accumulator model recapitulates both mouse and human behavior. The model and subjects' performance imply that the initial spikes in V1 can trigger a correct response, but subsequent V1 activity degrades performance. Supporting this hypothesis, optogenetically suppressing mask-evoked activity in V1 fully restores accurate behavior. Together, these results demonstrate that mice, like humans, are susceptible to masking and that target and mask information is first confounded downstream of V1.
Topics: Humans; Mice; Animals; Perceptual Masking; Visual Cortex; Photic Stimulation; Visual Perception
PubMed: 37957319
DOI: 10.1038/s41593-023-01488-0 -
Brain and Cognition Nov 2023Masked word repetition increases "old" responses on an episodic recognition test (Jacoby & Whitehouse, 1989). This effect is commonly attributed to perceptual fluency;...
Masked word repetition increases "old" responses on an episodic recognition test (Jacoby & Whitehouse, 1989). This effect is commonly attributed to perceptual fluency; that is, unconscious perception of the prime speeds reading of the target and this fluency leads to elevated familiarity. Two experiments directly tested the claim that perceptual fluency is responsible for word priming effects. Experiment 1 held prime-target meaning constant and altered the physical characteristics of match primes (e.g., "RIGHT" primes "RIGHT") by including both lowercase (e.g, "right") and mixed case primes (e.g., "rIgHt"). If word priming effects are due to perceptual fluency, then lowering the perceptual overlap between the prime and target should decrease or eliminate word priming effects. Instead, all three conditions showed robust priming effects in the behavioral and ERP (i.e., N400) measures. Experiment 2 equated the prime-target perceptual features and lowered the conceptual overlap by using orthographically similar nonwords as primes (e.g., "JIGHT" primes "RIGHT"). Removing prime-target conceptual overlap eliminated behavioral evidence of priming and N400 ERP differences correlated with priming. The evidence suggests that word priming effects on episodic recognition memory are more likely a product of conceptual fluency than perceptual fluency.
Topics: Humans; Male; Female; Evoked Potentials; Electroencephalography; Reaction Time; Recognition, Psychology; Memory, Episodic; Reading; Perceptual Masking; Repetition Priming
PubMed: 37783019
DOI: 10.1016/j.bandc.2023.106089 -
BioRxiv : the Preprint Server For... Oct 2023Visual detection is a fundamental natural task. Detection becomes more challenging as the similarity between the target and the background in which it is embedded...
Visual detection is a fundamental natural task. Detection becomes more challenging as the similarity between the target and the background in which it is embedded increases, a phenomenon termed "similarity masking". To test the hypothesis that V1 contributes to similarity masking, we used voltage sensitive dye imaging (VSDI) to measure V1 population responses while macaque monkeys performed a detection task under varying levels of target-background similarity. Paradoxically, we find that during an initial transient phase, V1 responses to the target are enhanced, rather than suppressed, by target-background similarity. This effect reverses in the second phase of the response, so that in this phase V1 signals are positively correlated with the behavioral effect of similarity. Finally, we show that a simple model with delayed divisive normalization can qualitatively account for our findings. Overall, our results support the hypothesis that a nonlinear gain control mechanism in V1 contributes to perceptual similarity masking.
PubMed: 37503133
DOI: 10.1101/2023.07.06.547970 -
JASA Express Letters Jun 2024Age-related changes in auditory processing may reduce physiological coding of acoustic cues, contributing to older adults' difficulty perceiving speech in background...
Age-related changes in auditory processing may reduce physiological coding of acoustic cues, contributing to older adults' difficulty perceiving speech in background noise. This study investigated whether older adults differed from young adults in patterns of acoustic cue weighting for categorizing vowels in quiet and in noise. All participants relied primarily on spectral quality to categorize /ɛ/ and /æ/ sounds under both listening conditions. However, relative to young adults, older adults exhibited greater reliance on duration and less reliance on spectral quality. These results suggest that aging alters patterns of perceptual cue weights that may influence speech recognition abilities.
Topics: Humans; Cues; Speech Perception; Aged; Young Adult; Female; Male; Adult; Perceptual Masking; Noise; Aging; Speech Acoustics; Middle Aged; Phonetics; Age Factors; Adolescent
PubMed: 38884558
DOI: 10.1121/10.0026371 -
Behavioral Sciences (Basel, Switzerland) Sep 2023How people recognize linguistic and emotional prosody in different listening conditions is essential for understanding the complex interplay between social context,...
How people recognize linguistic and emotional prosody in different listening conditions is essential for understanding the complex interplay between social context, cognition, and communication. The perception of both lexical tones and emotional prosody depends on prosodic features including pitch, intensity, duration, and voice quality. However, it is unclear which aspect of prosody is perceptually more salient and resistant to noise. This study aimed to investigate the relative perceptual salience of emotional prosody and lexical tone recognition in quiet and in the presence of multi-talker babble noise. Forty young adults randomly sampled from a pool of native Mandarin Chinese with normal hearing listened to monosyllables either with or without background babble noise and completed two identification tasks, one for emotion recognition and the other for lexical tone recognition. Accuracy and speed were recorded and analyzed using generalized linear mixed-effects models. Compared with emotional prosody, lexical tones were more perceptually salient in multi-talker babble noise. Native Mandarin Chinese participants identified lexical tones more accurately and quickly than vocal emotions at the same signal-to-noise ratio. Acoustic and cognitive dissimilarities between linguistic prosody and emotional prosody may have led to the phenomenon, which calls for further explorations into the underlying psychobiological and neurophysiological mechanisms.
PubMed: 37887450
DOI: 10.3390/bs13100800 -
Neuropsychologia Apr 2024Ambient sound can mask acoustic signals. The current study addressed how echolocation in people is affected by masking sound, and the role played by type of sound and...
Ambient sound can mask acoustic signals. The current study addressed how echolocation in people is affected by masking sound, and the role played by type of sound and spatial (i.e. binaural) similarity. We also investigated the role played by blindness and long-term experience with echolocation, by testing echolocation experts, as well as blind and sighted people new to echolocation. Results were obtained in two echolocation tasks where participants listened to binaural recordings of echolocation and masking sounds, and either localized echoes in azimuth or discriminated echo audibility. Echolocation and masking sounds could be either clicks or broad band noise. An adaptive staircase method was used to adjust signal-to-noise ratios (SNRs) based on participants' responses. When target and masker had the same binaural cues (i.e. both were monoaural sounds), people performed better (i.e. had lower SNRs) when target and masker used different types of sound (e.g. clicks in noise-masker or noise in clicks-masker), as compared to when target and masker used the same type of sound (e.g. clicks in click-, or noise in noise-masker). A very different pattern of results was observed when masker and target differed in their binaural cues, in which case people always performed better when clicks were the masker, regardless of type of emission used. Further, direct comparison between conditions with and without binaural difference revealed binaural release from masking only when clicks were used as emissions and masker, but not otherwise (i.e. when noise was used as masker or emission). This suggests that echolocation with clicks or noise may differ in their sensitivity to binaural cues. We observed the same pattern of results for echolocation experts, and blind and sighted people new to echolocation, suggesting a limited role played by long-term experience or blindness. In addition to generating novel predictions for future work, the findings also inform instruction in echolocation for people who are blind or sighted.
Topics: Animals; Humans; Sound Localization; Blindness; Noise; Acoustics; Cues; Perceptual Masking; Acoustic Stimulation
PubMed: 38342179
DOI: 10.1016/j.neuropsychologia.2024.108822