Isolating cognitive modules with the dual-task paradigm: Are speech perception and production separate processes?

A dual-task paradigm is used to investigate whether the auditory input logogen is distinct from the articulatory output logogen. In the first two experiments it is shown that the task of detecting an unspecified name in an auditory input stream can be combined with reading aloud visually presented words with relatively little single- to dual-task decrement. The stimuli for both tasks are independent streams of random words presented at rapid rates. A series of control experiments suggest that the first task places a considerable information processing load on the auditory input logogen, the second a considerable load on the phonological output logogen, and that subjects do not switch between the two tasks. The fact that the two tasks can be combined with ease is therefore interpreted as supporting the view that the systems underlying reading aloud and listening are separate. The ease of performance when the input streams are in different modalities, compared to the difficulties when they are in the same, has implications for general models of attention.     

The relationship between auditory temporal processing,phonemic awareness,and reading disability

Recent research suggests an auditory temporal deficit as a possible contributing factor to poor phonemic awareness skills. This study investigated the relationship between auditory temporal processing of nonspeech sounds and phonological awareness ability in children with a reading disability, aged 8-12 years, using Tallal's tone-order judgement task. Normal performance on the tone-order task was established for 36 normal readers. Forty-two children with developmental reading disability were then subdivided by their performance on the tone-order task. Average and poor tone-order subgroups were then compared on their ability to process speech sounds and visual symbols, and on phonological awareness and reading. The presence of a tone-order deficit did not relate to performance on the order processing of speech sounds, to poorer phonological awareness or to more severe reading difficulties. In particular, there was no evidence of a group by interstimulus interval interaction, as previously described in the literature, and thus little support for a general auditory temporal processing difficulty as an underlying problem in poor readers. In this study, deficient order judgement on a nonverbal auditory temporal order task (tone task) did not underlie phonological awareness or reading difficulties.     

Infant information processing and family history of specific language impairment: converging evidence for RAP deficits from two paradigms

An infant's ability to process auditory signals presented in rapid succession (i.e. rapid auditory processing abilities [RAP]) has been shown to predict differences in language outcomes in toddlers and preschool children. Early deficits in RAP abilities may serve as a behavioral marker for language-based learning disabilities. The purpose of this study is to determine if performance on infant information processing measures designed to tap RAP and global processing skills differ as a function of family history of specific language impairment (SLI) and/or the particular demand characteristics of the paradigm used. Seventeen 6- to 9-month-old infants from families with a history of specific language impairment (FH+) and 29 control infants (FH-) participated in this study. Infants' performance on two different RAP paradigms (head-turn procedure [HT] and auditory-visual habituation/recognition memory [AVH/RM]) and on a global processing task (visual habituation/recognition memory [VH/RM]) was assessed at 6 and 9 months. Toddler language and cognitive skills were evaluated at 12 and 16 months. A number of significant group differences were seen: FH+ infants showed significantly poorer discrimination of fast rate stimuli on both RAP tasks, took longer to habituate on both habituation/recognition memory measures, and had lower novelty preference scores on the visual habituation/recognition memory task. Infants' performance on the two RAP measures provided independent but converging contributions to outcome. Thus, different mechanisms appear to underlie performance on operantly conditioned tasks as compared to habituation/recognition memory paradigms. Further, infant RAP processing abilities predicted to 12- and 16-month language scores above and beyond family history of SLI. The results of this study provide additional support for the validity of infant RAP abilities as a behavioral marker for later language outcome. Finally, this is the first study to use a battery of infant tasks to demonstrate multi-modal processing deficits in infants at risk for SLI.     

Visual processing speed: effects of auditory input on visual processing

The ability to process simultaneously presented auditory and visual information is a necessary component underlying many cognitive tasks. While this ability is often taken for granted, there is evidence that under many conditions auditory input attenuates processing of corresponding visual input. The current study investigated infants' processing of visual input under unimodal and cross-modal conditions. Results of the three reported experiments indicate that different auditory input had different effects on infants' processing of visual information. In particular, unfamiliar auditory input slowed down visual processing, whereas more familiar auditory input did not. These results elucidate mechanisms underlying auditory overshadowing in the course of cross-modal processing and have implications on a variety of cognitive tasks that depend on cross-modal processing.     

Hearing what the eyes see: auditory encoding of visual temporal sequences

When the senses deliver conflicting information, vision dominates spatial processing, and audition dominates temporal processing. We asked whether this sensory specialization results in cross-modal encoding of unisensory input into the task-appropriate modality. Specifically, we investigated whether visually portrayed temporal structure receives automatic, obligatory encoding in the auditory domain. In three experiments, observers judged whether the changes in two successive visual sequences followed the same or different rhythms. We assessed temporal representations by measuring the extent to which both task-irrelevant auditory information and task-irrelevant visual information interfered with rhythm discrimination. Incongruent auditory information significantly disrupted task performance, particularly when presented during encoding; by contrast, varying the nature of the rhythm-depicting visual changes had minimal impact on performance. Evidently, the perceptual system automatically and obligatorily abstracts temporal structure from its visual form and represents this structure using an auditory code, resulting in the experience of "hearing visual rhythms."     

Attentional modulation of electrophysiological activity in auditory cortex for unattended sounds within multistream auditory environments

In three experiments, we addressed the issue of attention effects on unattended sound processing when one auditory stream is selected from three potential streams, creating a simple model of the cocktail party situation. We recorded event-related brain potentials (ERPs) to determine the way in which unattended, task-irrelevant sounds were stored in auditory memory (i.e., as one integrated stream or as two distinct streams). Subjects were instructed to ignore all the sounds and attend to a visual task or to selectively attend to a subset of the sounds and perform a task with the sounds (Experiments 1 and 2). A third (behavioral) experiment was conducted to test whether global pattern violations (used in Experiments 1 and 2) were perceptible when the sounds were segregated. We found that the mismatch negativity ERP component, an index of auditory change detection, was evoked by infrequent pattern violations occurring in the unattended sounds when all the sounds were ignored, but not when attention was focused on a subset of the sounds. The results demonstrate that multiple unattended sound streams can segregate by frequency range but that selectively attending to a subset of the sounds can modify the extent to which the unattended sounds are processed. These results are consistent with models in animal and human studies showing that attentional control can limit the processing of unattended input in favor of attended sensory inputs, thereby facilitating the ability to achieve behavioral goals.     

The Swedish Hayling task,and its relation to working memory,verbal ability,and speech‐recognition‐in‐noise

Cognitive functions and speech‐recognition‐in‐noise were evaluated with a cognitive test battery, assessing response inhibition using the Hayling task, working memory capacity (WMC) and verbal information processing, and an auditory test of speech recognition. The cognitive tests were performed in silence whereas the speech recognition task was presented in noise. Thirty young normally‐hearing individuals participated in the study. The aim of the study was to investigate one executive function, response inhibition, and whether it is related to individual working memory capacity (WMC), and how speech‐recognition‐in‐noise relates to WMC and inhibitory control. The results showed a significant difference between initiation and response inhibition, suggesting that the Hayling task taps cognitive activity responsible for executive control. Our findings also suggest that high verbal ability was associated with better performance in the Hayling task. We also present findings suggesting that individuals who perform well on tasks involving response inhibition, and WMC, also perform well on a speech‐in‐noise task. Our findings indicate that capacity to resist semantic interference can be used to predict performance on speech‐in‐noise tasks.     

Effects of auditory input in individuation tasks

Under many conditions auditory input interferes with visual processing, especially early in development. These interference effects are often more pronounced when the auditory input is unfamiliar than when the auditory input is familiar (e.g. human speech, pre‐familiarized sounds, etc.). The current study extends this research by examining how auditory input affects 8‐ and 14‐month‐olds’ performance on individuation tasks. The results of the current study indicate that both unfamiliar sounds and words interfered with infants’ performance on an individuation task, with cross‐modal interference effects being numerically stronger for unfamiliar sounds. The effects of auditory input on a variety of lexical tasks are discussed.     

Developmental differences in the allocation of processing capacity

Recently psychologists have formulated a comprehensive view of attention involving allocation of processing capacity. Although developmental changes in processing capacity have been proposed as one source of age differences in certain cognitive skills, there has been little systematic investigation of this hypothesis. In the present study, second and sixth graders and adults (8, 12, and 20 years of age, respectively) performed a letter-matching task (primary task) concurrently with an auditory detection task (secondary task). Changes in reaction time in the secondary task as a function of manipulations of the primary task were used to estimate capacity allocation to the primary task. Primary task variables included stage of processing (alerting, encoding, rehearsing, responding) and matching condition (physical-identity vs name-identity matching). Age differences in secondary task performance were found to be related to stage of processing but not to matching condition. Earlier stages of the letter match task (alerting, encoding) required somewhat more capacity allocation in younger subjects. Later stages (rehearsing, responding) made substantially higher demands on capacity in children. Capacity allocation may be an important cognitive variable mediating developmental differences in basic information processing skills, and may underlie age trends found in performance of certain complex cognitive tasks.     

Measurement of auditory cues in drivers' distraction

A driving simulator was used to examine the effects on driving performance of auditory cues in an in-vehicle information search task. Drivers' distraction by the search tasks was measured on a peripheral detection task. The difficulty of the search task was systematically varied to test the distraction caused by a quantified visual load. 58 participants completed the task. Performance on both search tasks and peripheral detection tasks was measured by mean response time and percent error. Analyses indicated that in-vehicle information search performance can be severely degraded when a target is located within a group of diverse distractors. Inclusion of an auditory cue in the visual search increased the mean response time as a result of a change in modality from auditory to visual. Inclusion of such an auditory cue seemed to influence distraction as measured by performance on the peripheral detection task; accuracy was lower when auditory cues were provided, and responses were slower when no auditory cues were provided. Distraction by the auditory cue varied according to the difficulty of the search task.     

The effects of divided attention on information processing in manual tracking.

Six subjects performed a manual tracking task concurrently uith each of two secondary tasks: in input task (auditory signal detection) and an output task (application of a constant force). A feedback-control analysis of tracking performance was utilized to analyze the time-sharing decrements observed in mean squared errer, in terms of components due to processing delay, addition of internal processing noise, and change in response bias (tracking gain). The results indicated that only the parameters measuring noise and gain were sensitive to time-sharing conditions, and these only to concurrent performance of the force application task. It is concluded that limits of attention in dual-task performance are more severe in output than in input stages of processing, but that these limits are not necessarily those of a single-channel bottleneck. Instead, a broader conception of attention is proposed: one that included changes in processing noise and shifts in response bias, as attention-related phenomena.     

Mental ability,P300, and mismatch negativity: Analysis of frequency and duration discrimination

Individual differences in mental ability (MA) were examined with event-related potentials (ERP). In addition to using an auditory frequency discrimination task, a duration discrimination task was used to elicit P300 and mismatch negativity (MMN) components of the ERP. Frequency and duration P300 latencies explained 9% and 10% of variance of MAB performance scores independently of each other and commonly 28% of variance. The finding that duration P300 latency explained variance of MA independent of that explained by frequency P300 latency, suggests that temporal information processing is partly dissociable from processing of frequency information in its prediction of MA. Duration and frequency MMNs were shown to be indices of discrimination ability and predicted 11% of variance of MAB performance scores. The outcome of the present study not only emphasizes the importance of both mental speed and discrimination ability for MA but also points to the significance of duration- and frequency-related ERP measures for the understanding of underlying brain mechanisms.     

The processing of deviant information in prediction and evaluation

Analyses of information integration and of retention were used to examine the processing of deviant information in prediction and evaluation tasks. Sets of test scores were presented serially for a group of hypothetical students, and subjects were asked to evaluate the performance of each student or predict each student’s performance on a comprehensive final exam. An averaging model with greater weight for the more recent scores than for the earlier scores was supported for both types of task, but the recency was more pronounced in the prediction task. Weighting of deviant scores differed in the prediction and evaluation tasks. Significant discounting (underweighting) of deviant scores was obtained only in the prediction task, The ability to recall deviant scores on uncued tests of retention was higher in the prediction task than in the evaluation task. Prediction of future performance based on inconsistent measures of past performance thus appears to be an active process involving the discovery and discounting of unrepresentative information.     

Age-related changes in processing auditory stimuli during visual attention: evidence for deficits in inhibitory control and sensory memory.

Age-related declines in attention and cognition have been associated with a difficulty in inhibiting the processing of task-irrelevant information (i.e., the inhibitory deficit hypothesis). However, evidence supporting the inhibitory deficit hypothesis remains equivocal, in part because of complexities in examining the processing of irrelevant stimuli using purely behavioral techniques. The effects of age on the processing of task-irrelevant stimuli were examined using scalp-recorded event-related brain potentials. Participants performed a visual discrimination task while standard and deviant auditory stimuli were presented in the background. Deviant auditory stimuli generated a mismatch negativity (MMN) wave that decreased with age, in part because of an age-related enhancement in sensory-evoked responses. The age-related changes in processing task-irrelevant auditory stimuli are consistent with the inhibitory deficit hypothesis and suggest that impaired inhibitory control of sensory input may play a role in the age-related declines in performance during selective attention tasks.     

The Role of Information Reduction in Skill Acquisition

Theories of skill acquisition assume that the effects of practice on task performance are due to either qualitative changes in the task structure, an increased efficiency of performing individual task components, an increased efficiency of performing sequences of task components, or some combination of these mechanisms. We propose an extension to the existing theories by arguing that for many tasks, practice affects which information is processed. More specifically, we argue that people learn, over the course of practice, to separate task-relevant from task-redundant information, and to limit their processing to relevant aspects of the task. In three experiments, subjects verified alphabetic strings, such as M [4] R S T. Strings were correct if they followed the alphabet when the number of letters, given by the digit in parentheses, was skipped. Strings were constructed such that errors occurred only within the initial “letter–digit–letter” triplet. Analyses of subjects’ RTs for strings of varying lengths demonstrated that: (a) subjects were able to distinguish relevant from redundant task information, and to limit their processing to the relevant information, (b) the ability to reduce the amount of information that is processed takes time and develops gradually over the course of practice, and (c) the mechanism underlying this ability appears to be largely stimulus-independent in the sense that structural components of a task are ignored, rather than specific task information. The findings and their implications for general theories of skill acquisition are discussed.     

多任务信息加工中的多道分时机制

学术界常用结构理论和资源理论来解释人在多任务信息加工中的作业表现。在多任务中起主要作用的认知能力,其表现形式主要为信息处理的速率以及加工和存储的容量。本研究利用多任务和任务速率的变化来研究信息处理的速率和多任务作业成绩的关系,认为大脑运行的时钟速率是资源的一种形式,大脑对该资源的分配采用多道分时的机制,某个任务获得的时间片越多,该任务的工作绩效就越好。研究表明,在一定的负荷下,信号速率的加快,任务数量的增加,人的作业成绩随着可用时间片的减少而下降。     

Position Location on Topographical Maps: Effects of Task Factors,Training, and Strategies

There is little research on the ways people go about the very common task of extracting information from various forms of maps. In this study, we examined task factors, cognitive processes, and individual differences as determinants of performance differences when locating a position on a topographical map from a given position on the ground. Subjects for the study were 188 Australian Army personnel. Both spatial visualization ability and a visual learning style preference were found to be effective predictors of performance, whereas a form of verbal strategy training produced significantly improved performance. When no effective strategy was supplied, those subjects with a strong visual learning style preference performed dramatically better than their low-preference counterparts, suggesting that this form of processing preference may have a powerful impact on untrained performance. These results indicate that most subjects usually approach the task of map reading in a relatively passive way, without any coherent strategy, and then attempt to encode information using inefficient spatial codes. When a simple and effective verbal strategy was supplied, most subjects were able to adopt it, with uniformly beneficial, results. This suggests that performance on many spatial tasks could be improved by verbal strategy training.     

Dopaminergic medication alters auditory distractor processing in Parkinson's disease

Parkinson's disease (PD) patients show signs of cognitive impairment, such as executive dysfunction, working memory problems and attentional disturbances, even in the early stages of the disease. Though motor symptoms of the disease are often successfully addressed by dopaminergic medication, it still remains unclear, how dopaminergic therapy affects cognitive function. The main objective of this study was to assess the effect of dopaminergic medication on visual and auditory attentional processing. 14 PD patients and 13 matched healthy controls performed a three-stimulus auditory and visual oddball task while their EEG was recorded. The patients performed the task twice, once on- and once off-medication. While the results showed no significant differences between PD patients and controls, they did reveal a significant increase in P3 amplitude on- vs. off-medication specific to processing of auditory distractors and no other stimuli. These results indicate significant effect of dopaminergic therapy on processing of distracting auditory stimuli. With a lack of between group differences the effect could reflect either 1) improved recruitment of attentional resources to auditory distractors; 2) reduced ability for cognitive inhibition of auditory distractors; 3) increased response to distractor stimuli resulting in impaired cognitive performance; or 4) hindered ability to discriminate between auditory distractors and targets. Further studies are needed to differentiate between these possibilities.