Processing capacity requirements of stimulus encoding.

Processing capacity requirements of stimulus encoding are examined in the light of conflicting evidence from studies by Posner and Boies (1971) and Comstock (1973). Capacity demand is assessed by impairment in performance on a secondary probe detection task at the moment of encoding on the primary task. The results support Comstock's (1973) conclusion that stimulus encoding does require processing capacity and relate capacity demand to the level of encoding difficulty. Evidence suggests that it costs more capacity to share attention between two modalities rather than within one. The importance of secondary task sensitivity in assessing capacity requirements is also illustrated.     

Microsaccadic modulation of response times in spatial attention tasks

Covert shifts of attention are usually reflected in RT differences between responses to valid and invalid cues in the Posner spatial attention task. Such inferences about covert shifts of attention do not control for microsaccades in the cue-target interval. We analyzed the effects of microsaccade orientation on RTs in four conditions, crossing peripheral visual and auditory cues with peripheral visual and auditory discrimination targets. Reaction time was generally faster on trials without microsaccades in the cue-target interval. If microsaccades occurred, the target-location congruency of the last microsaccade in the cue-target interval interacted in a complex way with cue validity. For valid visual cues, irrespective of whether the discrimination target was visual or auditory, target-congruent microsaccades delayed RT. For invalid cues, target-incongruent microsaccades facilitated RTs for visual target discrimination but delayed RT for auditory target discrimination. No reliable effects on RT were associated with auditory cues or with the first microsaccade in the cue-target interval. We discuss theoretical implications on the relation about spatial attention and oculomotor processes.     

The inability to ignore auditory distractors as a function of visual task perceptual load

Using a response competition paradigm, we investigated the ability to ignore target response-compatible, target response-incompatible, and neutral visual and auditory distractors presented during a visual search task. The perceptual load model of attention (e.g., Lavie & Tsal, 1994) states that task-relevant processing load determines irrelevant distractor processing in such a way that increasing processing load prevents distractor processing. In three experiments, participants searched sets of one (easy search) or six (hard search) similar items. In Experiment 1, visual distractors influenced reaction time (RT) and accuracy only for easy searches, following the perceptual load model. Surprisingly, auditory distractors yielded larger distractor compatibility effects (median RT for incompatible trials minus median RT for compatible trials) for hard searches than for easy searches. In Experiments 2 and 3, during hard searches, consistent RT benefits with response-compatible and RT costs with response-incompatible auditory distractors occurred only for hard searches. We suggest that auditory distractors are processed regardless of visual perceptual load but that the ability to inhibit cross-modal influence from auditory distractors is reduced under high visual load.     

Speed of lower-level auditory and visual processing as a basic factor in dyslexia: electrophysiological evidence

This study investigated speed of processing (SOP) among college-level adult dyslexic and normal readers in nonlinguistic and sublexical linguistic auditory and visual oddball tasks, and a nonlinguistic cross-modal choice reaction task. Behavioral and electrophysiological (ERP) measures were obtained. The results revealed that between both groups, reaction times (RT) were longer and the latencies of P2 and P3 components occurred later in the visual as compared to auditory oddball tasks. RT and ERP latencies were longest in the cross-modal task. RT and ERP latencies were delayed among dyslexic as compared to normal readers across tasks. On the oddball tasks, group differences in brain activity were observed only when responding to low-probability targets. These differences were largest for the P3 component, and most pronounced in the case of phonemes. The gap between ERP latencies in the visual versus the auditory modalities for each component was larger among dyslexic as compared to normal readers, and was particularly evident at the linguistic level. A hypothesis is proposed that suggests an amodal, basic SOP deficit among dyslexic readers. The slower cross-modal SOP is attributed to slower information processing in general and to disproportionate "asynchrony" between SOP in the visual versus the auditory system. It is suggested that excessive asynchrony in the SOP of the two systems may be one of the underlying causes of dyslexics' impaired reading skills.     

Nonspatial attentional shifts between audition and vision

This study investigated nonspatial shifts of attention between visual and auditory modalities. The authors provide evidence that the modality of a stimulus (S1) affected the processing of a subsequent stimulus (S2) depending on whether they shared the same modality. For both vision and audition, the onset of S1 summoned attention exogenously to its modality, causing a delay in processing S2 in a different modality. That undermines the notion that auditory stimuli have a stronger and more automatic alerting effect than visual stimuli (M. I. Posner, M. J. Nissen, & R. M. Klein, 1976). The results are consistent with other recent studies showing cross-modal attentional limitation. The authors suggest that such cross-modal limitation can be produced by simply presenting S1 and S2 in different modalities and that central processing mechanisms are also, at least partially, modality dependent.     

Metabolic control and auditory information processing at altered glucose levels in insulin-dependent diabetes

Previous work with a visual reaction time (RT) paradigm showed rate of mental processing to be slowed during a state of brain energy depletion (i.e., hypoglycemia). The present study employed an analog auditory RT paradigm to determine if modality differences in processing information might occur in response to glucose alteration. A balanced crossover design was used in which men with insulin-dependent diabetes completed RT tasks of increasing complexity at each of the following glucose levels: hypoglycemia (60 mg/dL), normoglycemia/control (110 mg/dL), and hyperglycemia (300 mg/dL). Results revealed two performance groups. A convergent group displayed slower RT responding during hypoglycemia, consistent with the visual RT pattern of results. A divergent group displayed better responding on one RT measure during hypoglycemia, and generally poorer responding on all RT measures during the other glucose conditions. Subjects in the divergent group maintained more stringent metabolic control and tended to have experienced more episodes of hypoglycemic unconsciousness. The present results provide the first evidence that more stringent metabolic control may be related to generally slower rates of processing auditory information. Possible explanations for these findings include hypotheses of immutable structual derangement, state-dependent performance effects, and a U-shaped response curve.     

Reaction time and temporal serial judgment: corroboration or dissociation?]

Dissociations between a motor response and the subject's verbal report have been reported from various experiments that investigated special experimental effects (e.g., metacontrast or induced motion). To examine whether similar dissociations can also be observed under standard experimental conditions, we compared reaction times (RT) and temporal order judgments (TOJ) to visual and auditory stimuli of three intensity levels. Data were collected from six subjects, each of which served for nine sessions. The results showed a strong, highly significant modality dissociation: While RTs to auditory stimuli were shorter than RTs to visual stimuli, the TOJ data indicated longer processing times for auditory than for visual stimuli. This pattern was found over the whole range of intensities investigated. Light intensity had similar effects on RT and TOJ, while there was a marginally significant tendency of tone intensity to affect RT more strongly than TOJ. It is concluded that modality dissociation is an example of "direct parameter specification", where the pathway from stimulus to response in the simple RT experiment is (at least partially) separate from the pathway that leads to a conscious, reportable representation. Two variants of this notion and alternatives to it are discussed.     

The effect of mechanical context on attentional cost in unimanual coordination

The purpose of this study was to address the attentional cost of sensorimotor coordination by determining if changes to the mechanical context of movement would influence the ability to attend and respond to an alternate stimulus. Nine right-handed participants performed rhythmic pronation and supination movements of the forearm in time with an auditory metronome. A secondary task, consisting of a pedal response to visual probe stimuli, was employed to infer the attentional cost of the coordination task. When the axis-of-rotation (AOR) was placed below the long axis of the forearm, the average time to react (RT) to the probe stimuli was greater for the supinate-on-the-beat condition than for the pronate-on-the-beat condition. Conversely, with the AOR above the forearm, RT for the pronate-on-the-beat pattern was greater than that for the supinate-on-the-beat pattern. Thus, changing the mechanical context of an upper limb coordination task altered the central processing cost required to maintain pattern stability. This finding provides further evidence that the attentional resources required to produce a particular movement are determined by the ease with which the action is executed by the sensorimotor system.     

Do alerting signals increase the size of the attentional focus?

Previous research has shown that the presentation of an auditory alerting signal before a visual target increases the interference from flanking distractors. Recently, it has been suggested that this increase in interference may be due to an expansion of the spatial focus of attention. In five experiments, this hypothesis was tested by using a probe technique dedicated to measuring variations in the size of the attentional focus: In the majority of trials, participants performed a letter discrimination task in which their attention was focused on a central target letter. In a randomly intermixed probe task, the size of the attentional focus was measured by letting participants respond to a probe occurring at varying positions. In all experiments, reaction time (RT) to the probe increased from the most central to more lateral probe positions. This V-shaped probe-RT function, however, was not flattened by the presentation of an alerting signal. Overall, this pattern of results is inconsistent with the hypothesis that alerting signals increase the attentional focus. Instead, it is consistent with nonspatial accounts that attribute the increase in interference to an alerting effect on perceptual processing, which then leads to a detrimental effect at the level of response selection.     

Accessory stimulation in the time course of visuomotor information processing: stimulus intensity effects on reaction time and response force

A series of three visual choice-reaction time experiments were performed to systematically investigate the effects of accessory auditory stimulation on response time (RT) and response force (RF). In Experiment 1, the effect of accessory auditory stimulation on early visual information processing was investigated. Experiments 2 and 3 were designed to examine the effects of accessory intensity on RT and RF across the entire time course of sensorimotor processing. Accessory stimulation accelerated response speed only when presented within 100 ms after onset of the visual response signal. An enhancing effect of accessory stimulation on RF, however, was found as late as 220 ms after onset of the response signal. These findings support the notion that response speed and response dynamics represent functionally independent sensorimotor phenomena.     

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.     

Programming strategies for rapid aiming movements under simple and choice reaction time conditions

Increases in reaction time (RT) as a function of response complexity have been shown to differ between simple and choice RT tasks. Of interest in the present study was whether the influence of response complexity on RT depends on the extent to which movements are programmed in advance of movement initiation versus during execution (i.e., online). The task consisted of manual aiming movements to one or two targets (one- vs. two-element responses) under simple and choice RT conditions. The probe RT technique was employed to assess attention demands during RT and movement execution. Simple RT was greater for the two- than for the single-target responses but choice RT was not influenced by the number of elements. In both RT tasks, reaction times to the probe increased as a function of number of elements when the probe occurred during movement execution. The presence of the probe also caused an increase in aiming errors in the simple but not choice RT task. These findings indicated that online programming was occurring in both RT tasks. In the simple RT task, increased executive control mediated the integration between response elements through the utilization of visual feedback to facilitate the implementation of the second element.     

Marker identification and mental rotation in automatic conditions

A basic finding of mental rotation research is that the time required to discriminate an asymmetrical visual stimulus from its reflected or backward version typically varies systematically with the angular departure of the probe stimulus from its normal upright (or expected) position within the picture plane. This regular dependence of reaction time (RT) on the rotational position (orientation) of the probe stimulus was interpreted by assuming an internal process working as a kind of mental analog of an external physical rotation and being carried out to bring the internal representations of the stimuli into congruence with each other before a decision is made. The present study was designed to investigate whether the dependence of RT on orientation also holds true in the case of a probe that can be identified on the basis of a single distinctive feature. In addition, it was examined whether the efficiency of the underlying processes could be improved by training. Results showed that the dependence of RT on orientation (RT function) does not occur if the presented visual probes differ with regard to a simple feature as, for example, an easily detectable angular difference. A change of the RT function, which would have indicated a change in the speed of the underlying processes, did not occur despite an "automatization" training.     

Programming strategies for rapid aiming movements under simple and choice reaction time conditions

Increases in reaction time (RT) as a function of response complexity have been shown to differ between simple and choice RT tasks. Of interest in the present study was whether the influence of response complexity on RT depends on the extent to which movements are programmed in advance of movement initiation versus during execution (i.e., online). The task consisted of manual aiming movements to one or two targets (one- vs. two-element responses) under simple and choice RT conditions. The probe RT technique was employed to assess attention demands during RT and movement execution. Simple RT was greater for the two- than for the single-target responses but choice RT was not influenced by the number of elements. In both RT tasks, reaction times to the probe increased as a function of number of elements when the probe occurred during movement execution. The presence of the probe also caused an increase in aiming errors in the simple but not choice RT task. These findings indicated that online programming was occurring in both RT tasks. In the simple RT task, increased executive control mediated the integration between response elements through the utilization of visual feedback to facilitate the implementation of the second element.     

媒体多任务的效用：听觉信息干扰和视听信息整合的实验证据

采用心理旋转范式和词汇判断范式,探讨媒体多任务经验不同者,在听觉信息干扰和视听信息整合情境下对图形一致性和真假词的判断表现。结果发现：(1)以判断图形一致性为实验任务,在无声和低音干扰条件下,低经验组的正确率均显著高于高经验组,两组的反应时差异均不显著;在高音干扰条件下,高经验组的反应时显著短于低经验组,正确率则没有显著差异。(2)以真假词判断为实验任务,对真词的判断,在三种听觉条件下,高经验组在语音匹配条件下的反应时最短,与低经验组无显著差异,但正确率显著高于低经验组,与另两种听觉条件没有显著差异;低经验组在语音匹配条件下的反应时显著长于另两种听觉条件,正确率则显著高于无声条件,与不匹配条件差异不显著。对假词的判断,低经验组在三种听觉条件下的反应时均显著短于高经验组,正确率与高经验组均无显著差异。研究表明,媒体多任务经验丰富者相比经验缺乏者受到任务无关的纯短高音干扰的影响要小一些,在需要视听通道语义整合的加工中具有一定的优势。     

The On-line Study of Sentence Comprehension: An Examination of Dual Task Paradigms

This paper presents three studies which examine the susceptibility of sentence comprehension to intrusion by extra-sentential probe words in two on-line dual-task techniques commonly used to study sentence processing: the cross-modal lexical priming paradigm and the unimodal all-visual lexical priming paradigm. It provides both a general review and a direct empirical examination of the effects of task-demand in the on-line study of sentence comprehension. In all three studies, sentential materials were presented to participants together with a target probe word which constituted either a better or a worse continuation of the sentence at a point at which it was presented. Materials were identical for all three studies. The manner of presentation of the sentence materials was, however, manipulated; presentation was either visual, auditory (normal rate) or auditory (slow rate). The results demonstrate that a technique in which a visual target probe interrupts ongoing sentence processing (such as occurs in unimodal visual presentation and in very slow auditory sentence presentation) encourages the integration of the probe word into the on-going sentence. Thus, when using such ‘sentence interrupting’ techniques, additional care to equate probes is necessary. Importantly, however, the results provide strong evidence that the standard use of fluent cross-modality sentence investigation methods are immune from such external probe word intrusions into ongoing sentence processing and are thus accurately reflect underlying comprehension processes.     

Re-evaluating visual and auditory dominance through modality switching costs and congruency analyses

Competition between the senses can lead to modality dominance, where one sense influences multi-modal processing to a greater degree than another. Modality dominance can be influenced by task demands, speeds of processing, contextual influence and practice. To resolve previous discrepancies in these factors, we assessed modality dominance in an audio-visual paradigm controlling for the first three factors while manipulating the fourth. Following a uni-modal task in which auditory and visual processing were equated, participants completed a pre-practice selective attention bimodal task in which the congruency relationship and task-relevant modality changed across trials. Participants were given practice in one modality prior to completing a post-practice selective attention bimodal task similar to the first. The effects of practice were non-specific as participants were speeded post-practice relative to pre-practice. Congruent stimuli relative to incongruent stimuli, also led to increased processing efficiency. RT data tended to reveal symmetric modality switching costs whereas the error rate data tended to reveal asymmetric modality switching costs in which switching from auditory to visual processing was particularly costly. The data suggest that when a number of safeguards are put in place to equate auditory and visual responding as far as possible, evidence for an auditory advantage can arise.     

The relation between physical stimulus properties and the effect of foreperiod duration on reaction time

Seven subjects were used in an experiment on the relation between signal modality and the effect of foreperiod duration (EP) on RT. With visual signals the usually reported systematic increase of RT as a function of FP duration (1, 5 and 15 s) was confirmed; with auditory signals no difference was found between FP's of 1 and 5 s while the effect at 15 s was equivalent to that found at 5 s with the visual signal. The results suggest that besides factors such as time uncertainty the FP effect is also largely dependent on the arousing quality of the signal.     

视-听跨通道汉语词汇信息加工中的抑制机制

采用选择性再认的方法考察在汉语词汇加工过程中 ,视 -听跨通道信息与视觉单通道信息加工过程中的抑制机制。结果表明 :对于视觉词汇的总体再认“否”反应 ,单通道干扰条件下的成绩优于跨通道干扰条件下的成绩。在视觉词汇加工过程中 ,对外在干扰材料的抑制效率不受输入干扰刺激的通道的影响。抑制效率受干扰材料语义关系性的影响 ,与目标材料属于同一语义范畴的比异范畴的干扰材料更难以被抑制。     

A developmental study of the auditory Stroop effect

A pediatric auditory version of the Stroop procedure was developed and administered to 48 normal children from 3 to 6 years of age. Our purpose was to define the developmental course characterizing interaction between auditory and semantic speech dimensions in young children. The procedure was a reaction time (RT) task that required children to respond as quickly and as accurately as possible to words spoken by a male or a female voice. Children were instructed to ignore what was said and to push the "Mommy" button if Mommy was talking or the "Daddy" button if Daddy was talking. Performance was obtained for words with neutral, congruent, and conflicting semantic content. Preschool children manifested processing dependencies that were similar to those observed in adults on the visual Stroop procedure. Conflict between semantic and auditory dimensions significantly increased RT and congruence between the two dimensions significantly decreased RT relative to the neutral condition. The pattern of results indicated that the meaning of words was processed automatically in the normal children. The magnitude of the Stroop effect reflected developmental change with increasing age.