Interruption management in the intensive care unit: Predicting resumption times and assessing distributed support.

Interruptions are frequent in many work domains. Researchers in health care have started to study interruptions extensively, but their studies usually do not use a theoretically guided approach. Conversely, researchers conducting theoretically rich laboratory studies on interruptions have not usually investigated how effectively their findings account for humans working in complex systems such as intensive care units. In the current study, we use the memory for goals theory and prospective memory theory to investigate which properties of an interruption influence how long it takes nurses to resume interrupted critical care tasks. We collected data with a mobile eye tracker in an intensive care unit and developed multiple regression models to predict resumption times. In 55.8% of all interruptions there was a finite—and therefore analyzable—resumption lag. For these cases, the main regression model explained 30.9% (adjusted R2) of the variance. Longer interruptions (β = .36, p p     

Mitigating disruptive effects of interruptions through training: What needs to be practiced?

It is generally accepted that, with practice, people improve on most tasks. However, when tasks have multiple parts, it is not always clear what aspects of the tasks practice or training should focus on. This research explores the features that allow training to improve the ability to resume a task after an interruption, specifically focusing on task-specific versus general interruption/resumption-process mechanisms that could account for improved performance. Three experiments using multiple combinations of primary tasks and interruptions were conducted with undergraduate psychology students. The first experiment showed that for one primary and interruption task-pair, people were able to resume the primary task faster when they had previous practice with the interruption. The second experiment replicated this finding for two other sets of primary and interruption task-pairs. Finally, the third experiment showed that people were able to resume a primary task faster only when they had previous practice with that specific primary and interruption task-pair. Experience with other primary and interruption task-pairs, or practice on the primary task alone, did not facilitate resumption. This suggests that a critical component in resuming after an interruption is the relationship between two tasks. These findings are in line with a task-specific mechanism of resumption and incompatible with a general-process mechanism. These findings have practical implications for developing training programs and mitigation strategies to lessen the disruptive effects of interruptions which plague both our personal and professional environments. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Contextual cues aid recovery from interruption: The role of associative activation.

A series of experiments introduced interruptions to the execution phase of simple Tower of London problems and found that the opportunity for preparation before the break in task reduced the time cost at resumption. Retrieval of the suspended goal was facilitated when participants were given the opportunity to encode retrieval cues during an "interruption lag" (the brief time before engaging in the interrupting task) but was impeded when these visual cues were subsequently altered following interruption. The results provide useful support for the goal-activation model (E. M. Altmann & G. J. Trafton, 2002), which assumes that context--at the points of both goal suspension and goal retrieval--is critical to efficient interruption recovery. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Improving memory after interruption: Exploiting soft constraints and manipulating information access cost.

Forgetting what one was doing prior to interruption is an everyday problem. The recent soft constraints hypothesis (Gray, Sims, Fu, & Schoelles, 2006) emphasizes the strategic adaptation of information processing strategy to the task environment. It predicts that increasing information access cost (IAC: the time, and physical and mental effort involved in accessing information) encourages a more memory-intensive strategy. Like interruptions, access costs are also intrinsic to most work environments, such as when opening documents and e-mails. Three experiments investigated whether increasing IAC during a simple copying task can be an effective method for reducing forgetting following interruption. IAC was designated Low (all information permanently visible), Medium (a mouse movement to uncover target information), or High (an additional few seconds to uncover such information). Experiment 1 found that recall improved across all three levels of IAC. Subsequent experiments found that High IAC facilitated resumption after interruption, particularly when interruption occurred on half of all trials (Experiment 2), and improved prospective memory following two different interrupting tasks, even when one involved the disruptive effect of using the same type of resource as the primary task (Experiment 3). The improvement of memory after interruption with increased IAC supports the prediction of the soft constraints hypothesis. The main disadvantage of a high access cost was a reduction in speed of task completion. The practicality of manipulating IAC as a design method for inducing a memory-intensive strategy to protect against forgetting is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interruption of the Tower of London task: Support for a goal-activation approach.

Unexpected interruptions introduced during the execution phase of simple Tower of London problems incurred a time cost when the interrupted goal was retrieved, and this cost was exacerbated the longer the goal was suspended. Furthermore, time taken to retrieve goals was greater following a more complex interruption, indicating the processing limitations may be as important as time-based limitations in determining the ease of goal retrieval. Such findings cannot simply be attributed to task-switching costs and are evaluated in relation to current models of goal memory (E. M. Altmann & G. J. Trafton, 2002; J. R. Anderson & S. Douglass, 2001), which provide a useful basis for the investigation and interpretation of interruption effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of interruptions on postcompletion and other procedural errors: An account based on the activation-based goal memory model.

A postcompletion error (PCE) is a specific kind of cognitive slip that involves omitting a final task step after the main goal of the task is accomplished. It is notoriously difficult to provoke (and hence study) slips under experimental conditions. In this paper, the authors present an experimental task paradigm that has been shown to be effective for studying PCEs in routine procedural tasks. Two studies were carried out to examine the effect of interruption position and task structure on the prevalence of PCEs. It was found that significantly more PCEs were obtained when an interruption occurred just before the PC step than when an interruption occurred at any other position in the task. The authors account for this effect in terms of Altmann and Trafton's activation-based goal memory model. The same interruption effect was obtained for some, but not all, other procedural errors; the authors discuss the nature of these errors and likely explanations for the differences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Time-related decay or interference-based forgetting in working memory?

The time-based resource-sharing model of working memory assumes that memory traces suffer from a time-related decay when attention is occupied by concurrent activities. Using complex continuous span tasks in which temporal parameters are carefully controlled, P. Barrouillet, S. Bernardin, S. Portrat, E. Vergauwe, & V. Camos (2007) recently provided evidence that any increase in time of the processing component of these tasks results in lower recall performance. However, K. Oberauer and R. Kliegl (2006) pointed out that, in this paradigm, increased processing times are accompanied by a corollary decrease of the remaining time during which attention is available to refresh memory traces. As a consequence, the main determinant of recall performance in complex span tasks would not be the duration of attentional capture inducing time-related decay, as Barrouillet et al. (2007) claimed, but the time available to repair memory traces, and thus would be compatible with an interference account of forgetting. The authors demonstrate here that even when the time available to refresh memory traces is kept constant, increasing the processing time still results in poorer recall, confirming that time-related decay is the source of forgetting within working memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Developmental change in working memory strategies: From passive maintenance to active refreshing.

Change in strategies is often mentioned as a source of memory development. However, though performance in working memory tasks steadily improves during childhood, theories differ in linking this development to strategy changes. Whereas some theories, such as the time-based resource-sharing model, invoke the age-related increase in use and efficiency of a strategy of active maintenance of memory traces, other theories, such as the task-switching model, do not mention strategy change. According to these models, either the cognitive load of the task or the duration of maintenance would account for recall performance. In the present study, we varied orthogonally these 2 factors. The results revealed that a different and unique factor affected recall performance at different ages: the duration of maintenance at age 6 and the cognitive load at age 7. As described by the task-switching model, younger children would not implement any maintenance activities while performing a concurrent task, their memory traces suffering from a time-based decay. This suggests that an increasing capacity of cognitive monitoring allows children to shift from this passive maintenance of memory traces to the active refreshing thereof at around the age of 7, reunifying the 2 current accounts of working memory development as 2 developmental stages. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Process analyses of the behavior of very young children in delay tasks.

Conducted 2 studies to examine the behavior of young children in tasks demanding self-control. In Study 1, 27 2-yr-olds were observed in 1 task. Behavior during the task was described using a 10-category coding system, and proportion scores derived from the 10-category coding system were correlated with total time in the task. Results show that 5 of the 10 correlations were significant. Behaviors bringing the goals into attention were negatively correlated with total delay time, whereas behaviors taking the goal out of attention tended to be positively associated with delay. In Study 2, 82 children (aged 24–36 mo) were observed in 3 delay tasks. The behavioral strategy studied was directing attention away from the goal object during delay periods. Significant effects were found for age and task type. When the sample was divided into shorter vs longer waiters, it was found that the longer waiters looked away from the goal for a larger proportion of the time. It is suggested that young children use implicit strategies for controlling their behavior in the face of a social demand. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Timing is affected by demands in memory search but not by task switching.

Recent studies suggest that timing and tasks involving executive control processes might require the same attentional resources. This should lead to interference when timing and executive tasks are executed concurrently. This study examined the interference between timing and task switching, an executive function. In 4 experiments, memory search and digit classification were performed successively in 4 conditions: search–search (search followed by search), search–digit, digit–search, and digit–digit. In a control reaction time (RT) condition, participants provided RT responses in each of the 2 tasks. In a time production condition, an RT response was provided to the first stimulus, but the response to the second stimulus, S2, was given only when participants judged that a previously presented target duration had elapsed. When responding to S2 required a switch, RTs to S2 were longer, but produced intervals were unaffected. These results show that memory search affects concurrent timing, but not task switching. Task switching seems therefore to be 1 executive function that does not interfer with timing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attentional resources in timing: interference effects in concurrent temporal and nontemporal working memory tasks

Three experiments examined interference effects in concurrent temporal and nontemporal tasks. The timing task in each experiment required subjects to generate a series of 2- or 5-sec temporal productions. The nontemporal tasks were pursuit rotor tracking (Experiment 1), visual search (Experiment 2), and mental arithmetic (Experiment 3). Each nontemporal task had two levels of difficulty. All tasks were performed under both single- and dual-task conditions. A simple attentional allocation model predicts bidirectional interference between concurrent tasks. The main results showed the classic interference effect in timing. That is, the concurrent nontemporal tasks caused temporal productions to become longer (longer productions represent a shortening of perceived time) and/or more variable than did timing-only conditions. In general, the difficult version of each nontemporal task disrupted timing more than the easier version. The timing data also exhibited a serial lengthening effect, in which temporal productions became longer across trials. Nontemporal task performance showed a mixed pattern. Tracking and visual search were essentially unaffected by the addition of a timing task, whereas mental arithmetic was disrupted by concurrent timing. These results call for a modification of the attentional allocation model to incorporate the idea of specialized processing resources. Two major theoretical frameworks--multiple resource theory and the working memory model--are critically evaluated with respect to the resource demands of timing and temporal/nontemporal dual-task performance.     

Immediate memory in sequential tasks.

Factors effecting the memory capacity are basic to understanding sequential tasks. The evidence indicates immediate memory is sometimes subject to decay, but that interference from interpolated items has a much larger effect. Interference effects are particularly great when the S must hold items in store while responding to previously stored material within an ongoing serial task. The ability of S to use time to reorganize the stimuli for storage works against the decay tendency. Only in rare instances does S store a pure representation of the stimulus; rather he must be viewed as an active information handler applying his knowledge of the nature of the stimulus and response to reduce his memory load. (56 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of chronic achievement motivation and achievement primes on the activation of achievement and fun goals.

This research examined the hypothesis that situational achievement cues can elicit achievement or fun goals depending on chronic differences in achievement motivation. In 4 studies, chronic differences in achievement motivation were measured, and achievement-denoting words were used to influence behavior. The effects of these variables were assessed on self-report inventories, task performance, task resumption following an interruption, and the pursuit of means relevant to achieving or having fun. Findings indicated that achievement priming (vs. control priming) activated a goal to achieve and inhibited a goal to have fun in individuals with chronically high-achievement motivation but activated a goal to have fun and inhibited a goal to achieve in individuals with chronically low-achievement motivation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Is There a Specific Executive Capacity for Dual Task Coordination? Evidence From Alzheimer's Disease.

Three experiments compared groups of Alzheimer's disease (AD) patients and healthy older and younger participants on visuospatial tracking and digit sequence recall, as single tasks and performed concurrently. In Experiment 1, tasks were performed concurrently with very low demand relative to span. Only the AD patients showed a dual task deficit. In Experiment 2, single task demand was manipulated on each task from below span to above span for each individual. All groups showed the same performance reductions with increasing demand. In Experiment 3, demand on 1 task was constant, whereas demand on the concurrent task was varied. AD patients showed a clear dual task deficit but were no more sensitive than control groups to varying demand. Results suggest an identifiable cognitive resource for dual task coordination within a multiple component working memory system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hippocampal and amygdaloid involvement in nonspatial and spatial working memory in rats: Effects of delay and interference.

Parametric manipulations of the task demand were used to examine the role of the hippocampus and amygdala in nonspatial and spatial working memory in male rats. Hippocampal lesions produced an immediate and long-lasting impairment of nonspatial working memory in an operant task. The memory deficits increased as the delay interval and the amount of proactive interference increased. Hippocampal lesions severely impaired spatial working memory in spatial alternation. Extensive postoperative testing reduced the magnitude of impairment of nonspatial but not spatial working memory. Amygdaloid lesions did not impair any aspect of performance in 2 tasks. The results suggest that the hippocampus, but not the amygdala, is involved in working memory and the task demand is a critical determinant for observing impairments of nonspatial working memory following hippocampal lesions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Immediate versus delayed visual memory task performance among schizophrenic patients and normal control subjects

In an exploratory study, 10 schizophrenic patients and 10 normal control subjects performed immediate and delayed memory tasks, which were variants of previously developed continuous performance tests. Both tasks required participants to identify five-digit numbers which were repeated. Numbers were presented in series for 500 ms each and separated by a 500-ms time-out period. In the immediate memory task, subjects were to respond if a number was identical to the one that had immediately preceded it. The delayed memory task differed from the first task in that a longer delay (3.5 s) between stimuli was introduced, and during this delay distracter stimuli appeared. While normal control subjects performed accurately on both tasks (exceeding 80% correct detections), schizophrenic patients performed poorly, performing worse on the delayed memory task than on the immediate memory task. Rates of commission errors (responses made to similar, but not identical numbers) were nearly equal between groups on the immediate memory task, but on the delayed memory task normal control subjects made relatively more commission errors while schizophrenic patients made fewer commission errors. No differences in response latencies were observed between subject groups or tasks. This paradigm may prove useful in discriminating subtle differences in immediate and delayed memory capability among psychiatric populations and normal control subjects.     

The cost of remembering to remember in event-based prospective memory: Investigating the capacity demands of delayed intention performance.

Prospective memory tasks are often accomplished during the performance of other activities. Despite the dual-task nature of prospective memory, little attention has been paid to how successful prospective memory performance affects ongoing activities. In the first 2 experiments, participants performing an embedded prospective memory task had longer response times on nonprospective memory target trials of a lexical decision task than participants performing the lexical decision task alone. In the prospective memory groups, longer lexical decision response times were associated with better prospective memory performance (Experiments 1, 2, and 3), a pattern not demonstrated with an embedded retrospective memory task (Experiment 2). The results of Experiment 3 suggest that the retrieval of a delayed intention, or the prospective component, can require capacity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Endothelin B receptor-mediated vasoconstriction induced by endothelin A receptor antagonist

BACKGROUND: Capacity limitation theories have proved to be surprisingly resilient in characterizing some of the cognitive deficits in schizophrenia. However, this perspective has not generally been applied to short-term verbal memory tasks. We explored this issue by first attempting to ascertain if gross misallocations of processing resources might explain impairments in short-term memory in schizophrenia on a classic digit span task and in a second study by attempting to determine what effects delay and memory set size had on a divided attention short-term verbal memory paradigm. METHODS: In the first study 16 patients with schizophrenia and 21 normal controls received 40 trials of a three digit task and 20 trials of a six digit span task. As the absolute number of digits presented and duration of presentation in two conditions were identical, subjects thus had equivalent 'opportunities' to make errors if distraction, in the sense of misallocation of cognitive resources, were at the root of poor performance. In the second study 15 patients with schizophrenia and 15 normal controls were tested in conditions in which two, four or six words were presented and in which rehearsal was prevented by an interference task (colour naming) for delays of 5, 10 or 15 s. RESULTS: Patients had disproportionate difficulty on the six digit rather than the three digit condition, suggesting that deficits in the verbal working memory short-term store may not be the result of attentional factors. In the second study, patients' performance was differentially worsened by the interference task, by memory set size (i.e. a capacity limitation) and by delay, a measure of decay rate. CONCLUSIONS: In concert, these studies demonstrate that schizophrenia patients have difficulties on verbal short-term memory span tasks not because of misallocation of resources, but rather because of limitations in 'representational capacity' and maintenance of information over delays.     

Optimizing Resource Utilization for Repetitive Construction Projects

Optimizing resource utilization can lead to significant reduction in the duration and cost of repetitive construction projects such as highways, high-rise buildings, and housing projects. This can be achieved by identifying an optimum crew size and interruption strategy for each activity in the project. Available dynamic programming formulations can be applied to provide solutions for this optimization problem; however, their application is limited, as they require planners to specify an arbitrary and an unbounded set of interruption options prior to scheduling. Such a requirement is not practical and may render the optimization problem infeasible. To circumvent the limitations of available formulations, this paper presents an automated and practical optimization model. The model utilizes dynamic programming formulation and incorporates a scheduling algorithm and an interruption algorithm so as to automate the generation of interruptions during scheduling. This transforms the consideration of interruption options, in optimizing resource utilization, from an unbounded and impractical problem to a bounded and feasible one. A numerical example from the literature is analyzed to illustrate the use and capabilities of the model.