Function Of Stimulus Onset Asynchrony Research Articles

Response competition better explains Stroop interference than does response exclusion

Researchers debate whether Stroop interference from an incongruent word in color-naming response time is caused by response competition or by response exclusion. According to the former account, the interference reflects competition in lexical response selection during color name planning, whereas according to the latter, the interference reflects the removal of a motor program for the incongruent word from an articulatory buffer after planning. Here, numerical predictions about the magnitude of Stroop interference as a function of stimulus onset asynchrony were derived from these accounts. These predictions were then tested on representative data in the literature. Measures of goodness-of-fit showed that the numerical predictions of a response competition account are closer to the empirical data than those of the response exclusion account. These results indicate that response competition provides a better explanation of interference in naming than does response exclusion.

The recalibration patterns of perceptual synchrony and multisensory integration after exposure to asynchronous speech

Perceptual synchrony and multisensory integration both vary as a function of stimulus onset asynchrony, but evidences from behavioral, patient, and lesion studies all support some dissociation between these two processes. Although it has been found that both perceptual synchrony and multisensory integration are recalibrated after exposure to asynchronous multisensory stimuli, no studies have directly compared these two recalibration patterns. We addressed this by using McGurk speech and requiring participants to perform simultaneity judgments and a syllable identification task in separate sessions. The results revealed that after exposure to asynchrony, both perceptual synchrony and McGurk fusion shifted toward the temporal lag. The recalibration aftereffects (i.e., the magnitude of shifts) of these two processes have no significant difference and correlation. In addition, McGurk fusion increased strongly at the direction of the temporal lag, which could not be fully explained by fusion shifts. Thus, the present research implies that recalibration patterns of explicit and implicit timing represented by perceptual synchrony and multisensory integration have both similarity and difference.

Perception of successive brief objects as a function of stimulus onset asynchrony: model experiments based on two-stage synchronization of neuronal oscillators

Recently we introduced a new version of the perceptual retouch model incorporating two interactive binding operations-binding features for objects and binding the bound feature-objects with a large scale oscillatory system that acts as a mediary for the perceptual information to reach consciousness-level representation. The relative level of synchronized firing of the neurons representing the features of an object obtained after the second-stage synchronizing modulation is used as the equivalent of conscious perception of the corresponding object. Here, this model is used for simulating interaction of two successive featured objects as a function of stimulus onset asynchrony (SOA). Model output reproduces typical results of mutual masking-with shortest and longest SOAs first and second object correct perception rate is comparable while with intermediate SOAs second object dominates over the first one. Additionally, with shortest SOAs misbinding of features to form illusory objects is simulated by the model.

Temporal order judgment in dyslexia—Task difficulty or temporal processing deficiency?

Dyslexia has been widely held to be associated with deficient temporal processing. It is, however, not established that the slower visual processing of dyslexic readers is not a secondary effect of task difficulty. To illustrate this we re-analyze data from Liddle et al. (2009) who studied temporal order judgment in dyslexia and plotted the results as d′ as a function of Stimulus Onset Asynchrony (SOA). These data make it possible to compare the results of dyslexic readers and controls both in terms of d′ which is related closely to task difficulty and in terms of time (i.e. SOA). It is found that the difference between the groups is about equally well accounted for in terms of d′ as in terms of temporal factors. This suggests that the results of Liddle et al. (2009) may be equally well accounted for in terms of general task difficulty as temporal factors.

Salience is only briefly represented: Evidence from probe-detection performance.

Salient objects in the visual field tend to capture attention. The present study aimed to examine the time-course of salience effects using a probe-detection task. Eight experiments investigated how the salience of different orientation singletons affected probe reaction time as a function of stimulus onset asynchrony (SOA) between the presentation of a singleton display and a probe display. The results demonstrate that salience consistently affected probe reaction time at the shortest SOA. The effect of salience disappeared as SOA increased. These results suggest that contrary to the assumption of major theories on visual selection, salience is transiently represented in our visual system allowing the effects of salience on attentional selection to be only short-lived.

Temporal onset-order discrimination through the tactual sense: Effects of frequency and site of stimulation

This research extends the study of temporal resolution of the tactual sensory system through measurements of temporal-onset order discrimination for continuous tonal signals addressing (a) the effects of frequency separation of the two stimuli whose onset orders are to be discriminated and (b) the effects of redundant coding of frequency and site of stimulation on performance. Sinusoidal signals were presented either at two separate digits (thumb and index finger of the left hand) or at a single site of stimulation (left index finger) using a multifinger tactual stimulation system. Measurements were obtained using a one-interval two-alternative forced choice procedure in which each interval consisted of the random-order presentation of two different stimuli with roving values of amplitude and duration. Thresholds were estimated from psychometric functions of d' as a function of stimulus-onset asynchrony (SOA). On average, temporal onset-order thresholds were larger for one-finger conditions (mean SOA of 74.8 ms) than for two-finger conditions (mean SOA of 48.5 ms) and decreased as frequency separation increased, particularly for single-site presentation. Redundant coding of frequency and site of stimulation resulted in higher resolution by a factor of 1.5 compared to frequency alone and by a factor of 1.2 compared to site alone.

Visibility Reflects Dynamic Changes of Effective Connectivity between V1 and Fusiform Cortex

Identifying the neural basis of visibility is central to understanding conscious visual perception. Visibility of basic features such as brightness is often thought to reflect activity in just early visual cortex. But here we show under metacontrast masking that fMRI activity in stimulus-driven areas of early visual cortex did not reflect parametric changes in the visibility of a brightness stimulus. The psychometric visibility function was instead correlated with activity in later visual regions plus parieto-frontal areas, and surprisingly, in representations of the unstimulated stimulus surround for primary visual cortex. Critically, decreased stimulus visibility was associated with a regionally-specific decoupling between early visual cortex and higher visual areas. This provides evidence that dynamic changes in effective connectivity can closely reflect visual perception.

Temporal onset-order discrimination through the tactual sense

Tactual temporal-onset order thresholds were measured for two sinusoidal vibrations of different frequencies delivered to two separate locations (thumb and index finger) of a multi-finger tactual stimulating device. The frequency delivered to the thumb was fixed at 50 Hz and that to the index finger at 250 Hz. The amplitude and duration of each of the two sinusoidal vibrations were roved independently from trial to trial in a 1-interval, 2AFC procedure. Performance, measured as a function of stimulus-onset asynchrony (SOA), indicated that the temporal-onset-order threshold averaged 34 ms across four subjects. The data were further classified into subsets according to both the amplitude and duration of the two stimuli in each trial of the roving-discrimination paradigm. The results indicated that the amplitude differences of the two stimuli in each trial had a substantial effect on onset-order discrimination, while duration differences generally had little effect. The effects of amplitude differences are explained qualitatively in terms of amplitude latency relationships and stimulus interactions such as temporal masking. Overall, the results not only contribute to an enhanced understanding of the temporal sensitivity of the tactual system but also provide guidelines for the design of tactual aids for hearing-impaired persons.

Bimodal and trimodal multisensory enhancement: Effects of stimulus onset and intensity on reaction time

Manual reaction times to visual, auditory, and tactile stimuli presented simultaneously, or with a delay, were measured to test for multisensory interaction effects in a simple detection task with redundant signals. Responses to trimodal stimulus combinations were faster than those to bimodal combinations, which in turn were faster than reactions to unimodal stimuli. Response enhancement increased with decreasing auditory and tactile stimulus intensity and was a U-shaped function of stimulus onset asynchrony. Distribution inequality tests indicated that the multisensory interaction effects were larger than predicted by separate activation models, including the difference between bimodal and trimodal response facilitation. The results are discussed with respect to previous findings in a focused attention task and are compared with multisensory integration rules observed in bimodal and trimodal superior colliculus neurons in the cat and monkey.

Transient and sustained effects of an auditory accessory stimulus in a visual go/no go task.

The present study examined the facilitation effects of an auditory accessory stimulus that was irrelevant to a visual reaction time (RT) task as a function of stimulus onset asynchrony between the accessory stimulus and the visual target stimulus. Results of the present experiment showed that the auditory accessory stimulus caused two variations of RT, short-term and long-term, that were distinguished on the basis of stimulus onset asynchrony. This finding suggested that effects of an accessory stimulus consisted of two qualitatively different facilitations. The Transient Facilitation appeared instantly after the onset of the accessory stimulus and then soon decayed, and the Sustained Facilitation increased and decreased more gradually than the former.

TRANSIENT AND SUSTAINED EFFECTS OF AN AUDITORY ACCESSORY STIMULUS IN A VISUAL GO/NO GO TASK

The present study examined the facilitation effects of an auditory accessory stimulus that was irrelevant to a visual reaction time (RT) task as a function of stimulus onset asynchrony between the accessory stimulus and the visual target stimulus. Results of the present experiment showed that the auditory accessory stimulus caused two variations of RT, short term and long-term, that were distinguished on the basis of stimulus onset asynchrony. This finding suggested that effects of an accessory stimulus consisted of two qualitatively different facilitations. The Transient Facilitation appeared instantly after the onset of the accessory stimulus and then soon decayed, and the Sustained Facilitation increased and decreased more gradually than the former.

Identity and similarity in repetition blindness: no cross-over interaction

The difficulty in reporting both occurrences of a repeated item is a phenomenon referred to as repetition blindness (RB). RB has been proposed to result from temporal limitations in creating separate episodic tokens for a twice-activated type. Recently, Chialant and Caramazza ( Cognition 63 (1997) 79–119) disputed the conventional view that RB for non-identical words (orthographic RB, as in lice and lick) results from the same mechanism as identity RB, and proposed that orthographic RB arises from competition for lexical selection. Supporting evidence was that identical and merely similar words showed different amounts of RB as a function of stimulus onset asynchrony (lag). Four experiments failed to replicate Chialant and Caramazza's finding that identity RB decreases, but orthographic RB increases, as a function of lag. Instead, RB for all stimuli, including homonym pairs, declined monotonically with lag. These results are consistent with a common mechanism underlying RB for identical and orthographically similar words and with prior research suggesting that RB in similar words occurs at a sublexical level.

Recall of two visual targets embedded in RSVP streams of distractors depends on their temporal and spatial relationship.

In the present study, I examined how the temporal and spatial relationship between two visual targets (T1 and T2) affects the recall of both targets when they are embedded in rapidly displayed distractors. Presented on a trial were two synchronized streams of characters, one to the left and the other to the right of the fixation. Independent of their spatial relationship, a U-shaped curve described the recall of the second target (T2) as a function of stimulus onset asynchrony (SOA) between T1 and T2. It indicated the presence of the attentional blink with a T2 deficit sparing up to about 150- to 200-msec SOA. However, T2 deficit was greater at short SOAs (up to about 250 msec) when T1 and T2 occurred at different locations than when they occurred at a common location. When SOA was short (100 msec or so), recall of T1 was impaired when T1 and T2 occurred at a common location, but not when they were at different locations. The present findings can be reconciled with existing models (e.g., the interference model and the two-stage model) by distinguishing automatic and controlled attention gating processes at the transfer of perceptual representations to a more durable storage (e.g., visual short-term memory).

Adult age differences in strategic and dynamic components of focusing visual attention

Changes in the width of a focally attended area were assessed by analysis of changes in reaction time associated with response-incompatible nontarget letters (flankers). In two experiments, the focus of attention widened as an increasing function of stimulus onset asynchrony (SOA). In contrast to the predictions of generalized slowing and inhibition-deficit models, this dynamic change in attention was comparable for young and older adults in both experiments. Evidence accumulation outside the focus of attention was greater for young adults than for older adults when target location varied (Experiment 2). This latter effect, however, was strategic (i.e., independent of SOA). Analyses of the task complexity functions (Brinley plots) indicated a greater contribution of generalized slowing when target location was constant (Experiment 1) than when location varied (Experiment 2).

Temporal impulse response functions for luminance and colour during saccades.

Previous work has shown that during saccadic eye movements, contrast sensitivity for low spatial frequency patterns modulated in luminance is selectively reduced by up to one logarithmic unit, while high spatial frequency patterns, and equiluminant patterns of all spatial frequencies are not suppressed at all [Burr et al. (1994). Nature, 371, 511-513]. Here we study the temporal characteristics for sensitivity to luminance and chromatic patterns during saccades, using the two-pulse summation technique. Sensitivity was measured for detecting two successive pulses as a function of stimulus-onset asynchrony, during normal viewing and during saccades. Impulse response functions were estimated from the summation data, for all conditions. For equiluminance, the functions were monophasic during normal viewing and saccades. For luminance modulation, the impulse response functions were di-phasic in both normal viewing and saccades. However, during saccades the impulse responses were faster in normal viewing. This result is consistent with the suggestion that saccadic suppression is mediated by contrast gain control mechanisms, known to occur in M-cells but not P-cells.

Texture-Based Tasks are Little Affected by Second Tasks Requiring Peripheral or Central Attentive Fixation

Experiments are described in which observers attempted to perform concurrently two separate visual tasks. Two types of tasks were used: the identification of a T-shaped or L-shaped letter target, and the detection or localization of a texture element of unique orientation (texture target) within a dense texture. Combining these tasks to form various task pairs, performance as a function of stimulus onset asynchrony (SOA) was established separately for each task in a pair. In addition, performance was measured when each task was carried out by itself. When paired, two identification tasks (T or L) on (two) letter targets required a significantly larger SOA than either identification task by itself. This outcome suggests the involvement of serial performance and competition for a limited resource, confirming that letter identification requires attentive fixation. However, when the identification of a central letter target was paired with the localization (upper or lower hemifield) of an eccentric texture target, performance in the pair was comparable to performance of each task by itself. This suggests parallel performance and a lack of conflict over resources. The outcome was similar when the identification of an eccentric letter target was paired with the detection (present or absent) of an eccentric texture target. These results are consistent with the possibility that localization and detection of a textural singularity do not require attentive fixation.

Suppression of visible persistence as a function of spatial separation between inducing stimuli

In the first of two experiments, suppression of the visible persistence of a temporally leading stimulus by a trailing stimulus was studied as a joint function of stimulus onset asynchrony (SOA) and of spatial proximity between the two stimuli. In agreement with earlier work, temporal integration between the two successive stimuli was progressively impaired as SOA was increased. In addition, degree of suppression of visible persistence was found to increase markedly with proximity. This confirms the outcome of earlier research that employed trains of successive stimuli seen in apparent motion. However, the present finding suggests that neither a seriated mode of display nor the appearance of coherent motion are necessary for the suppressive effect of spatial proximity. The results favor an account based on inhibitory interactions, rather than one based on spatiotemporal summation. Further predictions from inhibition theory-bearing on the luminance of the component stimuli-were tested and confirmed in a second experiment.

Masking efficiency as a function of stimulus onset asynchrony for spatial-frequency detection and identification.

Detection and identification thresholds for grating targets were measured in the presence of a compound mask grating as a function of the stimulus onset asynchrony (SOA). The detection and identification SOA functions are both reversed U-shaped but they are not parallel. The detection-to-identification ratio is itself a reversed U-shaped function of SOA, even for stimuli two octaves apart, with a peak between +20 and +60 ms SOA (backward masking). It is argued that these results support the hypothesis according to which detection and identification are serial processes.

Vibrotactile pattern recognition and discrimination at several body sites.

Although many body sites have been tested for the processing of vibrotactile patterns, very few studies have employed similar patterns and techniques to compare processing across loci. In the studies reported here, subjects judged comparable sets of spatial patterns presented in the same way to the finger, palm, and thigh in tests of recognition, discrimination, and masking. Discrimination varied as a function of stimulus onset asynchrony in a similar way across loci, but level of performance across sites depended, to different degrees, on duration. These differences were mirrored in the relative levels of recognition learning across sites. Levels of forward and backward masking on the fingers and thigh were less dependent on duration and site.

Initial microgenetic steps in single-glance face recognition

Single-glance recognition of a familiar face cannot be explained as perception of a mediating image and subsequent reasoning processes to identify the image. This recognition is too fast for a normal reasoning process, neither can it be verbalized as such a process. But that does not simply mean that the face is perceived “directly”. This pre-verbal high-speed identification seems only possible by means of tacit “micro-genetic” steps, which successively “actualize” the relevant information. When we present photographs of different familiar persons with film-speed on the same place, it seems possible to demonstrate this. It was hypothesized that the first portrait “triggers” directing “schemata”, capable of actualizing relevant information. This “processing” of the first portrait provides general information, which specifies the presence of a face in a particular position, and perhaps even possible sets of familiar faces. However, when a second portrait is presented after a critical interval, final identification steps, which originate from the previous phases, still have to be made. When both faces are in similar positions, these final tests are continued on the second portrait, in much the same way as must be the case with the next frame in a continuing shot of a movie picture. Especially when portraits also share common set reducing features, this interactive microgenesis initially produces a decreasing recognition function of stimulus onset asynchrony for the first portrait and simultaneously an increasing function for the second portrait. These results are also discussed in terms of backward and forward visual masking.