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PubMed1976

Age differences in central perceptual processing: a dichoptic backward masking investigation.

Age differences in central perceptual processing were investigated using young (mean age 19.5 years) and old (mean age 64.2 years) subjects in a backward masking paradigm known to produce central interference. Subjects were presented with symmetrical, straight-lined letters as target stimuli (TS). The masking stimulus (MS) was a pattern of line segments of the same width as the strokes of the letters spaced evenly over the part of the visual field occupied by the letters. The TS was presented to the right eye and followed by the MS to the left eye. A robust masking effect was found for both young and old across conditions in which TS energy was much greater than MS energy. The asynchrony between TS and MS onset (SOA) was found to be the variable describing escape from masking for both age groups. However, the older group required 24% longer SOAs than the young to escape masking, suggesting a slowing with age in central perceptual processing.

Adult↗
PubMed1988

Time course of the subjective contrast enhancement for a second stimulus in successively paired above-threshold transient forms: perceptual retouch instead of forward masking.

Subjects estimated apparent contrast of an invariant test stimulus (the letter H), exposed either after an inducing stimulus (from the set of 12 alternatives) with SOAs varying from 20 to 290 msec, or alone (a control condition). With inducing stimuli, at certain SOAs the subjective contrast of the TS was enhanced relative to single-stimulus control. This enhancement appeared as a curvilinear function of SOA with the most pronounced enhancement at SOA = 110 msec. The effect was present also if the Ss had to recognize the inducing, backward-masked stimulus (the recognition function being U-shaped). The enhancement effect increased with increase in the intensity-level of the inducer. The separate functions for the conditions of inducing letters of high and low figural similarity with TS were coinciding, thus pointing to the nonspecific nature of the obtained effect within the given spatial constraints (1 deg of the visual angle). A small forward masking effect present with SOAs less than or equal to 40 msec was rapidly replaced by the enhancement with increase in SOA. The results are discussed in terms of the visual masking theories and the hypothetical perceptual retouch mechanism.

Adult↗
PubMed1996

Attentional capture by abrupt onsets: new perceptual objects or visual masking?

The authors have shown that an object appearing abruptly in a previously blank location is efficiently detected in visual search when it is embedded in an array of objects without abrupt onset (term no-onset stimuli). In these experiments, no-onset stimuli appeared well before the onset stimulus but were camouflaged by additional line segments rendering the stimuli unidentifiable. B. S. Gibson (1996) claims that the availability of the no-onset stimuli was delayed relative to that of the abrupt onset stimulus because of forward masking. The authors show that forward masking is unlikely to be a significant factor in their experiments, and 3 new experiments are reported that undermine Gibson's masking account. Observed differences in the efficiency with which onset and no-onset stimuli are processed in visual search are due to attentional capture by new perceptual objects and to a relatively sluggish process of updating existing object representations.

Attention↗
PubMed2002

Rhythmic masking release: contribution of cues for perceptual organization to the cross-spectral fusion of concurrent narrow-band noises.

The contribution of temporal asynchrony, spatial separation, and frequency separation to the cross-spectral fusion of temporally contiguous brief narrow-band noise bursts was studied using the Rhythmic Masking Release paradigm (RMR). RMR involves the discrimination of one of two possible rhythms, despite perceptual masking of the rhythm by an irregular sequence of sounds identical to the rhythmic bursts, interleaved among them. The release of the rhythm from masking can be induced by causing the fusion of the irregular interfering sounds with concurrent "flanking" sounds situated in different frequency regions. The accuracy and the rated clarity of the identified rhythm in a 2-AFC procedure were employed to estimate the degree of fusion of the interferring sounds with flanking sounds. The results suggest that while synchrony fully fuses short-duration noise bursts across frequency and across space (i.e., across ears and loudspeakers), an asynchrony of 20-40 ms produces no fusion. Intermediate asynchronies of 10-20 ms produce partial fusion, where the presence of other cues is critical for unambiguous grouping. Though frequency and spatial separation reduced fusion, neither of these manipulations was sufficient to abolish it. For the parameters varied in this study, stimulus onset asynchrony was the dominant cue determining fusion, but there were additive effects of the other cues. Temporal synchrony appears to be critical in determining whether brief sounds with abrupt onsets and offsets are heard as one event or more than one.

Acoustic Stimulation↗
PubMed1985

Dichoptic priming effects on ambiguous picture processing.

The results of two experiments show that pictures, pattern masked to prevent conscious representation, could nevertheless influence the interpretation of supraliminally presented ambiguous pictures. This priming effect was obtained under conditions of dichoptic masking (Expt 1) and under conditions in which the picture primes were presented to one eye and the ambiguous pictures presented to the other eye (Expt 2). In obtaining priming under conditions of pattern masking, the results substantiate recent claims that pattern masking does not prevent perceptual processing. Instead, it appears to prevent the recovery of some of the products of perceptual processing necessary for conscious report. The findings are discussed within the framework of current models of picture processing.

Discrimination Learning↗
PubMed2005

Visibility, visual awareness, and visual masking of simple unattended targets are confined to areas in the occipital cortex beyond human V1/V2.

In visual masking, visible targets are rendered invisible by modifying the context in which they are presented, but not by modifying the targets themselves. Here, we localize the neuronal correlates of visual awareness in the human brain by using visual masking illusions. We compare monoptic visual masking activation, which we find within all retinotopic visual areas, with dichoptic masking activation, which we find only in those retinotopic areas downstream of V2. Because monoptic and dichoptic masking are equivalent in magnitude perceptually, the present results establish a lower bound for maintenance of visual awareness of simple unattended targets. Moreover, we find that awareness-correlated circuits for simple targets are restricted to the occipital lobe. This finding provides evidence of an upper boundary in the visual hierarchy for visual awareness of simple unattended targets, thus constraining the location of circuits that maintain the visibility of simple targets to occipital areas beyond V1/V2.

Adolescent↗
PubMed2005

The effect of spatial separation on informational masking of speech in normal-hearing and hearing-impaired listeners.

The ability to understand speech in a multi-source environment containing informational masking may depend on the perceptual arrangement of signal and masker objects in space. In normal-hearing listeners, Arbogast et al. [J. Acoust. Soc. Am. 112, 2086-2098 (2002)] found an 18-dB spatial release from a primarily informational masker, compared to 7 dB for a primarily energetic masker. This article extends the earlier work to include the study of listeners with sensorineural hearing loss. Listeners performed closed-set speech recognition in two spatial conditions: 0 degrees and 90 degrees separation between signal and masker. Three maskers were tested: (1) the different-band sentence masker was designed to be primarily informational; (2) the different-band noise masker was a control for the different-band sentence; and (3) the same-band noise masker was designed to be primarily energetic. The spatial release from the different-band sentence was larger than for the other maskers, but was smaller (10 dB) for the hearing-impaired group than for the normal-hearing group (15 dB). The smaller benefit for the hearing-impaired listeners can be partially explained by masker sensation level. However, the results suggest that hearing-impaired listeners can use the perceptual effect of spatial separation to improve speech recognition in the presence of a primarily informational masker.

Adult↗
PubMed2003

Evidence against response bias in temporal order tasks with attention manipulation by masked primes.

Attending to a location shortens the perceptual latency of stimuli appearing at this location (perceptual latency priming). According to attentional explanations, perceptual latency priming relies on the speeded transfer of attended visual information into an internal model. However, doubts about the attentional origin have repeatedly been raised because efforts to minimize response bias have been insufficient in most studies. Five experiments investigated the contribution of a response bias to perceptual latency priming (judgment bias due to the two-alternative forced-choice method and due to the existence of the prime, criterion effects or second-order bias, sensorimotor priming). If any, only small response biases were found. The results thus support the attentional explanation.

Adult↗
PubMed1993

Masking, information integration, and tactile pattern perception: a comparison of the isolation and integration hypotheses.

Two competing models of the effects of pattern element proximity, masking, and perceptual integration on the discriminability of spatiotemporal vibrotactile patterns are compared. Kirman's 'integration hypothesis' predicts that pattern perception is facilitated by a process of perceptual integration which requires that pattern elements be presented in close spatial and temporal proximity. Conversely, the 'isolation hypothesis' predicts that the strong masking effects which occur when pattern elements are presented in close proximity impede the perception of patterns. Traditional masking studies do not provide a fair test of these two hypothesis because they rely on methods that measure the subject's ability to identify the target when the target is presented in conjunction with the mask, rather than the discriminability of the complex percept resulting from the integration of the target and mask. To account for this, a new procedure was devised where the amount of interelement masking and the discriminability of the pattern as a whole were measured independently as the spatial and temporal separation of the pattern elements were varied. As expected under both hypotheses, masking between pattern elements increased as either the spatial or the temporal separation between them was decreased. The pattern discrimination data also support the isolation hypothesis in that the patterns were discriminated less well with increasing temporal element separation with a similar but nonsignificant trend in the case of spatial separation. It is concluded that this new methodology should be applied to a wider range of tactile pattern processing situations in order to assess the generality of the results obtained.

Adult↗
PubMed2003

Forward masking of faces by spatially quantized random and structured masks: on the roles of wholistic configuration, local features, and spatial-frequency spectra in perceptual identification.

The forward masking of faces by spatially quantized masking images was studied. Masks were used in order to exert different types of degrading effects on the early representations in facial information processing. Three types of source images for masks were used: Same-face images (with regard to targets), different-face images, and random Gaussian noise that was spectrally similar to facial images. They were all spatially quantized over the same range of quantization values. Same-face masks had virtually no masking effect at any of the quantization values. Different-face masks had strong masking effects only with fine-scale quantization, but led to the same efficiency of recognition as in the same-face mask condition with the coarsest quantization. Moreover, compared with the noise-mask condition, coarsely quantized different-face masks led to a relatively facilitated level of recognition efficiency. The masking effect of the noise mask did not vary significantly with the coarseness of quantization. The results supported neither a local feature processing account, nor a generalized spatial-frequency processing account, but were consistent with the microgenetic configuration-processing theory of face recognition. Also, the suitability of a spatial quantization technique for image configuration processing research has been demonstrated.

Adult↗
PubMed1978

Age differences in peripheral perceptual processing: a monoptic backward masking investigation.

Peripheral processes in vision were investigated in two experiments involving monoptic backward masking with random noise. For young and old subjects, peripheral processing time (represented by stimulus onset asynchrony of target and mask) was characterized as a power function of target energy. Although processing time for both age groups showed a similar rate of decline with increasing target energy, old subjects processed targets more slowly at all energy levels. Results were independent of education, sex, and criterion differences between young and old. Target duration was related to critical interstimulus interval, such that stimulus onset asynchrony between target and mask was approximately constant for a given target energy within each age group. Evidence suggests that peripheral processing begins with target onset and that processing time is best characterized by a power function relating stimulus onset asynchrony of target and mask to target energy.

Adult↗
PubMed1995

Perceptual organization in a comodulation masking release interference paradigm: exploring the role of amplitude modulation, frequency modulation, and harmonicity.

Two areas of interest within auditory scene analysis are the identification of cues which contribute to auditory grouping and/or segregation, and the methodology employed to measure such effects. The present study explored the roles of three purported grouping cues--correlated AM, correlated FM, and harmonicity--using a comodulation masking release interference paradigm. This method was reasoned to be free of alterations in the subject's mode of listening (analytic versus synthetic). The results suggested that correlated AM was a viable grouping cue. For some listeners, the presence of FM also appeared to provide a grouping cue, but, generally, no effect of coherence of FM was observed. No effect of harmonicity was observed in this paradigm.

Adult↗
PubMed1995

Activation by marginally perceptible ("subliminal") stimuli: dissociation of unconscious from conscious cognition.

Introduces a linear regression method for investigating unconscious cognition. For words that were obscured by simultaneous dichoptic masking, indirect effects (semantic priming) and direct effects (perceptual identification) were assessed in 20 experiments (total N = 2,026). When measures of both indirect and direct effects have rational zero points, a statistically significant intercept in the indirect-on-direct-measure regression shows that (a) the indirect effect occurred in the absence of the direct effect, and (b) unconscious cognition is involved. For a position discrimination task, but not for an evaluative decision task, indirect-on-direct regression showed the significant intercept effect. Although small in magnitude, this intercept effect provides the statistically most secure finding yet obtained of a much-sought and controversial data pattern--indirect effect with no direct effect. With one added assumption (which appears plausible for the present data), this pattern indicates that unconscious cognition is dissociated from (i.e., occurs separately from) conscious cognition.

Cognition↗