The differential contribution of executive functions to temporal generalisation,reproduction and verbal estimation

Evidence from dual-task studies suggests that executive resources are recruited during timing. However, there has been little exploration of whether executive recruitment is universal across temporal tasks, or whether different temporal tasks recruit different executive resources. The current study explored this further by examining how individual differences in updating, switching, inhibition and access affected performance on temporal generalisation, reproduction and verbal estimation tasks. It was found that temporal tasks differentially loaded onto different executive resources. Temporal generalisation performance was related to updating and access ability. Reproduction performance was related to updating, access and switching. Verbal estimation performance was only related to access. The results suggest that executive resources may be recruited when monitoring and maintaining multiple durations in memory at the same time, and when retrieving duration representations from long-term memory. The findings emphasise the need to consider timing behaviour as the product of a wide range of complex, integrated, cognitive systems, rather than as the output of a clock in isolation.     

Crossmodal action selection: Evidence from dual-task compatibility

Response-related mechanisms of multitasking were studied by analyzing simultaneous processing of responses in different modalities (i.e., crossmodal action). Participants responded to a single auditory stimulus with a saccade, a manual response (single-task conditions), or both (dual-task condition). We used a spatially incompatible stimulus-response mapping for one task, but not for the other. Critically, inverting these mappings varied temporal task overlap in dual-task conditions while keeping spatial incompatibility across responses constant. Unlike previous paradigms, temporal task overlap was manipulated without utilizing sequential stimulus presentation, which might induce strategic serial processing. The results revealed dual-task costs, but these were not affected by an increase of temporal task overlap. This finding is evidence for parallel response selection in multitasking. We propose that crossmodal action is processed by a central mapping-selection mechanism in working memory and that the dual-task costs are mainly caused by mapping-related crosstalk.     

Domain-general contributions to social reasoning: theory of mind and deontic reasoning re-explored

Using older adults and dual-task interference, we examined performance on two social reasoning tasks: theory of mind (ToM) tasks and versions of the deontic selection task involving social contracts and hazardous conditions. In line with performance accounts of social reasoning, evidence from both aging and the dual-task method suggested that domain-general resources contribute to performance of these tasks. Specifically, older adults were impaired relative to younger adults on all types of social reasoning tasks tested; performance varied as a function of the demands these tasks placed on domain-general resources. Moreover, in younger adults, simultaneous performance of a working memory task interfered with younger adults' performance on both types of social reasoning tasks; here too, the magnitude of the interference effect varied with the processing demands of each task. Limits placed on social reasoning by executive functions contribute a great deal to performance, even in old age and in healthy younger adults under conditions of divided attention. The role of potentially non-modular and modular contributions to social reasoning is discussed.     

Interference effects of stimulus–response modality pairings in dual tasks and their robustness

Recent evidence suggests that the degree of interference in dual-task situations depends crucially on the pairings of input- and output modalities of the two component tasks with increased dual-task costs for modality incompatible (i.e., visual–vocal and auditory–manual) compared to modality compatible (i.e., visual–manual and auditory–vocal) dual tasks. These effects of modality pairings in dual tasks have been related to the overlap of non-preferred processing pathways in modality incompatible tasks. Until now, modality compatibility has not yet been related to other sources of interference in a dual-task context, such as stimulus–response (S–R) compatibility or crosstalk. In the present study, we conducted two experiments using the paradigm of the psychological refractory period (PRP) to test the effects of S–R compatibility and crosstalk on the effects of modality compatibility in temporally overlapping task situations. Experiment 1 revealed an overadditive interaction between stimulus onset asynchrony and modality compatibility for tasks with S–R compatible mappings, indicating that modality compatibility effects are present in different task situations, even when S–R mappings are otherwise compatible. In Experiment 2, we aimed at pinpointing the boundaries of the effects of modality compatibility in dual-task situations. We showed that additional sources of dual-task interference in a modality compatible dual task could overwrite the pronounced PRP effect previously shown for modality incompatible tasks. Taken together, these data provide new evidence that the specific types of stimulus–response modality pairings are an additional factor that might interact with other sources of interference in dual-task situations.     

The role of control functions in mentalizing: dual-task studies of theory of mind and executive function

Conflicting evidence has arisen from correlational studies regarding the role of executive control functions in Theory of Mind. The current study used dual-task manipulations of executive functions (inhibition, updating and switching) to investigate the role of these control functions in mental state and non-mental state tasks. The 'Eyes' pictorial test of Theory of Mind showed specific dual-task costs when concurrently performed with an inhibitory secondary task. In contrast, interference effects on a verbal 'Stories' task were general, occurring on both mental state and non-mental state tasks, and across all types of executive function. These findings from healthy functioning adults should help to guide decisions about appropriate methods of assessing ToM in clinical populations, and interpreting deficits in performance in such tasks in the context of more general cognitive dysfunction.     

The neural effect of stimulus-response modality compatibility on dual-task performance: an fMRI study

Recent fMRI studies suggest that the inferior frontal sulcus (IFS) is involved in the coordination of interfering processes in dual-task situations. The present study aims to further specify this assumption by investigating whether the compatibility between stimulus and response modalities modulates dual-task-related activity along the IFS. It has been shown behaviorally that the degree of interference, as measured by dual-task costs, increases in modality-incompatible conditions (e.g. visual–vocal tasks combined with auditory–manual tasks) as compared to modality-compatible conditions (e.g. visual–manual tasks combined with auditory–vocal tasks). Using fMRI, we measured IFS activity when participants performed modality-compatible and modality-incompatible single and dual tasks. Behaviorally, we replicated the finding of higher dual-task costs for modality-incompatible tasks compared to modality-compatible tasks. The fMRI data revealed higher activity along the IFS in modality-incompatible dual tasks compared with modality-compatible dual tasks when inter-individual variability in functional brain organization is taken into account. We argue that in addition to temporal order coordination (Szameitat et al., 2002), the IFS is involved in the coordination of cognitive processes associated with the concurrent mapping of sensory information onto corresponding motor responses in dual-task situations.     

Dissociating controlled from automatic processing in temporal preparation

The aim of the present study was to investigate the controlled versus the automatic nature of temporal preparation. If temporal preparation involves controlled rather than automatic processing, it should be reduced by the addition of a concurrent demanding task. This hypothesis was tested by comparing participants' performance in a temporal preparation task that measured two main effects of temporal preparation (temporal orienting and sequential effects) between a single-task and a dual-task condition. In the single-task condition, participants responded to a visual target presented after symbolic cues that were highly predictive of the moment of target onset. In the dual-task condition, the temporal preparation task was performed concurrently with a working memory task. The results showed that sequential effects survived to dual-task interference, while temporal orienting was reduced as a function of the competition for executive resources required by both working memory and temporal preparation tasks. These findings provide direct behavioural evidence that temporal orienting and sequential effects involve dissociable cognitive processes.     

A common source of attention for auditory and visual tracking

Tasks that require tracking visual information reveal the severe limitations of our capacity to attend to multiple objects that vary in time and space. Although these limitations have been extensively characterized in the visual domain, very little is known about tracking information in other sensory domains. Does tracking auditory information exhibit characteristics similar to those of tracking visual information, and to what extent do these two tracking tasks draw on the same attention resources? We addressed these questions by asking participants to perform either single or dual tracking tasks from the same (visual–visual) or different (visual–auditory) perceptual modalities, with the difficulty of the tracking tasks being manipulated across trials. The results revealed that performing two concurrent tracking tasks, whether they were in the same or different modalities, affected tracking performance as compared to performing each task alone (concurrence costs). Moreover, increasing task difficulty also led to increased costs in both the single-task and dual-task conditions (load-dependent costs). The comparison of concurrence costs between visual–visual and visual–auditory dual-task performance revealed slightly greater interference when two visual tracking tasks were paired. Interestingly, however, increasing task difficulty led to equivalent costs for visual–visual and visual–auditory pairings. We concluded that visual and auditory tracking draw largely, though not exclusively, on common central attentional resources.     

Aging and time-sharing aspects of executive control

A particularly important aspect of executive functioning involves the ability to coordinate two simultaneous activities. The role of this aspect of executive functioning in adult-age differences in cognitive performance was examined in a study involving 150 adults between 20 and 91 years of age who performed the same visual-motor tracking task with three different primary tasks. The participants also performed several additional cognitive tasks that allowed examination of the relation of time-sharing efficiency to other types of cognitive functioning The results were consistent with the existence of a distinct time-sharing ability because the time-sharing costs in the three dual-task combinations were significantly correlated with one another but only weakly correlated with other cognitive variables. Increased age was associated with reductions in time-sharing ability, and greater efficiency in performing two tasks at once was associated with better performance on tasks assessing spatial, reasoning, and memory abilities. Although this pattern is what one would expect if executive processes contribute to age differences in cognitive functioning, the effects were smaller than those associated with a perceptual speed construct.     

Cued shifts of attention and memory encoding in partial report: A dual-task approach

This study explores how cued shifts of visual attention and rapid encoding of visual information relate to limited-capacity processing mechanisms. Three experiments were conducted placing a partial-report task within a dual-task paradigm. Experiments 1 and 2 involved a simple speeded visual discrimination (Task 1) and then an unspeeded partial-report task (Task 2). Generally, Task 2 accuracy declined as the temporal overlap between the two tasks increased. In addition, in Experiment 1, varying the number of items in the partial-report display had an effect on performance regardless of overlap. In contrast, in Experiment 2, varying the type of probe had an effect only at long task overlap. The generality of the interference effect was tested in Experiment 3 using an auditory discrimination as Task 1. Again, Task 2 accuracy declined as the temporal overlap between the two tasks increased. In all cases, the observed interference had the properties of a processing bottleneck. It is argued that encoding information into memory and response selection for the first task both require general-purpose processing. The results are discussed in terms of the functional relationship between attention and memory.     

提取干扰对知觉和概念启动的影响

通过学习—测验范式,分别以词汇判断、语义分类任务为测验,探讨提取干扰对不同识别式记忆的影响差异。结果发现,实验1验证了识别式知觉内隐记忆的提取干扰效应,实验2发现识别式概念内隐记忆在提取干扰下也明显降低;两个实验启动量联合分析发现,相比无干扰条件,概念启动比知觉启动受到提取干扰的破坏更大。上述结果说明识别式内隐记忆的提取干扰具有普遍性,提取干扰产生了不同识别式内隐记忆之间的分离,识别式概念内隐记忆更容易受到提取干扰的影响。     

Executive processes in visual and spatial working memory tasks

Three experiments are reported, which have investigated the nature of the cognitive mechanisms that underlie performance on specific visuo-spatial working memory tasks, with the emphasis on exploring the extent of central executive involvement. Experiments 1 and 2 employed oral random digit generation as an executive task within a dual-task paradigm. The results of both experiments indicated that visuo-spatial tasks that involve sequential processing of information show more interference with random digit generation than do visuo-spatial tasks that involve simultaneous processing. The third experiment substituted oral random digit generation for executive tasks that did not involve memory for serial order (vigilance tasks adapted from Vandierendonck, De Vooght, & Van der Goten, 1998b). The results indicated significant interference between the vigilance tasks and the sequential visuo-spatial task, but not with the simultaneous visuo-spatial task. Overall the results of the three experiments are interpreted as indicating that serial sequential visuo-spatial tasks involve executive resources to a significantly greater extent than do simultaneous visuo-spatial tasks, and that this can have implications for studies that attempt to make use of such tasks to fractionate separable visual and spatial components within working memory.     

Executive processes in visual and spatial working memory tasks

Three experiments are reported, which have investigated the nature of the cognitive mechanisms that underlie performance on specific visuo-spatial working memory tasks, with the emphasis on exploring the extent of central executive involvement. Experiments 1 and 2 employed oral random digit generation as an executive task within a dual-task paradigm. The results of both experiments indicated that visuo-spatial tasks that involve sequential processing of information show more interference with random digit generation than do visuo-spatial tasks that involve simultaneous processing. The third experiment substituted oral random digit generation for executive tasks that did not involve memory for serial order (vigilance tasks adapted from Vandierendonck, De Vooght, & Van der Goten, 1998b). The results indicated significant interference between the vigilance tasks and the sequential visuo-spatial task, but not with the simultaneous visuo-spatial task. Overall the results of the three experiments are interpreted as indicating that serial sequential visuo-spatial tasks involve executive resources to a significantly greater extent than do simultaneous visuo-spatial tasks, and that this can have implications for studies that attempt to make use of such tasks to fractionate separable visual and spatial components within working memory.     

The role of executive functions in human prospective interval timing

Human timing is thought to be based on the output of an internal clock. Whilst the functioning of this clock is well documented, it is unclear which other cognitive resources may moderate timing. Brown (2006) and Rattat (2010) suggest that the central executive of working memory may be recruited during timing. However it seems likely that the fractionated executive component processes identified by Miyake et al. (2000) and Fisk and Sharp (2004) may differentially contribute to timing performance; further exploration of this was the aim of the present study. An interference paradigm was employed in which participants completed an interval production task, and tasks which have been shown to tap the four key executive component processes (shifting, inhibition, updating and access) under single and dual-task conditions. Comparison of single and dual-task performance indicated that timing always became more variable when concurrently performing a second task. Bidirectional interference only occurred between the interval production task and the memory updating task, implying that both tasks are competing for the same executive resource of updating. There was no evidence in the current study to suggest that switching, inhibition or access was involved in timing, however they may be recruited under more difficult task conditions.     

The role of input and output modality pairings in dual-task performance: evidence for content-dependent central interference

Recent debate regarding dual-task performance has focused on whether costs result from limitations in central capacity, and whether central operations can be performed in parallel. While these questions are controversial, the dominant models of dual-task performance share the assumption that central operations are generic--that is, their interactions are independent of stimulus and response modalities. To examine these issues, we conducted a series of dual-task experiments with different input and output modality pairings. One condition combined a visual-manual task with an auditory-vocal task, and the other condition reversed the input-output pairings, combining a visual-vocal task with an auditory-manual task. Input/output modality pairings proved to be a key factor; throughout practice, dual-task costs were generally more than twice as large with visual-vocal/auditory-manual tasks than with the opposite arrangement of modalities (Experiments 1 and 2). These differences could be explained neither by competition for peripheral resources nor by differences in single-task response times (Experiment 3). Moreover, the persistent dual-task costs did not appear to stem from a central bottleneck. Contrary to the dominant models of dual-task performance, we propose that central interference between tasks depends not just on the duration of central operations, nor just strategic adaptation, but also on the content of those operations. Implications for structural and strategic accounts of dual-task interference are discussed.     

Do attentional capacities and processing speed mediate the effect of age on executive functioning?

The executive processes are well known to decline with age, and similar data also exists for attentional capacities and processing speed. Therefore, we investigated whether these two last nonexecutive variables would mediate the effect of age on executive functions (inhibition, shifting, updating, and dual-task coordination). We administered a large battery of executive, attentional and processing speed tasks to 104 young and 71 older people, and we performed mediation analyses with variables showing a significant age effect. All executive and processing speed measures showed age-related effects while only the visual scanning task performance (selective attention) was explained by age when controlled for gender and educational level. Regarding mediation analyses, visual scanning partially mediated the age effect on updating while processing speed partially mediated the age effect on shifting, updating and dual-task coordination. In a more exploratory way, inhibition was also found to partially mediate the effect of age on the three other executive functions. Attention did not greatly influence executive functioning in aging while, in agreement with the literature, processing speed seems to be a major mediator of the age effect on these processes. Interestingly, the global pattern of results seems also to indicate an influence of inhibition but further studies are needed to confirm the role of that variable as a mediator and its relative importance by comparison with processing speed.     

Timing and executive function: Bidirectional interference between concurrent temporal production and randomization tasks

A review of interference effects in concurrent temporal/nontemporal dual-task studies suggests that prospective timing may be related to executive cognitive functions. Executive processes play a supervisory role in behavior by controlling attention, coordinating information, and scheduling actions. In the present research, a timing task was paired with an established executive task in a dual-task paradigm. The timing task required subjects t o generate a series o f 5-sec temporal productions,and the executive task was random number generation. These tasks were performed both separately and concurrently. Comparisons of single-task and dual-task conditions showed that (1) the randomization task interfered with timing by making temporal productions more variable and longer and (2) concurrent timing disrupted randomization performance by making responses less random. This pattern of bidirectional interference supports the idea that timing relies on the same attentional resources used by other executive-level tasks.     

Dual-task automatization: The key role of sensory–motor modality compatibility

How do people automatize their dual-task performance through bottleneck bypassing (i.e., accomplish parallel processing of the central stages of two tasks)? In the present work we addressed this question, evaluating the impact of sensory–motor modality compatibility—the similarity in modality between the stimulus and the consequences of the response. We hypothesized that incompatible sensory–motor modalities (e.g., visual–vocal) create conflicts within modality-specific working memory subsystems, and therefore predicted that tasks producing such conflicts would be performed less automatically after practice. To probe for automaticity, we used a transfer psychological refractory period (PRP) procedure: Participants were first trained on a visual task (Exp. 1) or an auditory task (Exp. 2) by itself, which was later presented as Task 2, along with an unpracticed Task 1. The Task 1–Task 2 sensory–motor modality pairings were either compatible (visual–manual and auditory–vocal) or incompatible (visual–vocal and auditory–manual). In both experiments we found converging indicators of bottleneck bypassing (small dual-task interference and a high rate of response reversals) for compatible sensory–motor modalities, but indicators of bottlenecking (large dual-task interference and few response reversals) for incompatible sensory–motor modalities. Relatedly, the proportion of individuals able to bypass the bottleneck was high for compatible modalities but very low for incompatible modalities. We propose that dual-task automatization is within reach when the tasks rely on codes that do not compete within a working memory subsystem.

     

Temporal order in memory and interval timing: an interference analysis

The effect of varying load in memory tasks performed during a time interval production was examined. In a first experiment, increasing load in memory search for temporal order affected concurrent time production more strongly than varying load in a spatial memory task of equivalent difficulty. This result suggests that timing uses some specific resources also required in processing temporal order in memory, resources that would not be used in the spatial memory task. A second experiment showed that the interference between time production and memory search involving temporal order was stronger when, during the timing task, a decision was made on the temporal position of a memory item, than when information on temporal order was retained throughout the interval to be produced. These results underscore the importance of considering the specific resources and processes involved when the interference between timing and concurrent non-temporal tasks is analyzed.     

Do objects in working memory compete with objects in perception?

It is generally assumed that “perceptual object” is the basic unit for processing visual information and that only a small number of objects can be either perceptually selected or encoded in working memory (WM) at one time. This raises the question whether the same resource is used when objects are selected and tracked as when they are held in WM. In two experiments, we measured dual-task interference between a memory task and a Multiple Object Tracking task. The WM tasks involve explicit, implicit, or no spatial processing. Our results suggest there is no resource competition between working memory and perceptual selection except when the WM task requires encoding spatial properties.