Helen M. Hodgetts

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.

A multiperspective approach to the conceptualization of executive functions

The concept of executive function (EF) is deemed unclear and difficult to operationalize. We use a multiperspective approach to quantify and reduce the current proliferation of EFs. A literature review of 60 studies identified 68 subcomponents of EF: Through objective statistical techniques, these terms were reduced to 18 by removing semantic overlap (using latent semantic analysis) and psychometric overlap (using hierarchical cluster analysis). However, still such a large number of functions lacks parsimony. We therefore revisit the concept of EF and suggest that the many proposed subcomponents are not functions per se but rather a number of task-specific behaviors.

Attentional costs and failures in air traffic control notifications

Large display screens are common in supervisory tasks, meaning that alerts are often perceived in peripheral vision. Five air traffic control notification designs were evaluated in their ability to capture attention during an ongoing supervisory task, as well as their impact on the primary task. A range of performance measures, eye-tracking and subjective reports showed that colour, even animated, was less effective than movement, and notifications sometimes went unnoticed. Designs that drew attention to the notified aircraft by a pulsating box, concentric circles or the opacity of the background resulted in faster perception and no missed notifications. However, the latter two designs were intrusive and impaired primary task performance, while the simpler animated box captured attention without an overhead cognitive cost. These results highlight the need for a holistic approach to evaluation, achieving a balance between the benefits for one aspect of performance against the potential costs for another. Practitioner summary: We performed a holistic examination of air traffic control notification designs regarding their ability to capture attention during an ongoing supervisory task. The combination of performance, eye-tracking and subjective measurements demonstrated that the best design achieved a balance between attentional power and the overhead cognitive cost to primary task performance.

Distraction control processes in free recall: Benefits and costs to performance

How is semantic memory influenced by individual differences under conditions of distraction? This question was addressed by observing how participants recalled visual target words--drawn from a single category--while ignoring spoken distractor words that were members of either the same or a different (single) category. Working memory capacity (WMC) was related to disruption only with synchronous, not asynchronous, presentation, and distraction was greater when the words were presented synchronously. Subsequent experiments found greater negative priming of distractors among individuals with higher WMC, but this may be dependent on targets and distractors being comparable category exemplars. With less dominant category members as distractors, target recall was impaired--relative to control--only among individuals with low WMC. The results highlight the role of cognitive control resources in target-distractor selection and the individual-specific cost implications of such cognitive control.

Reminders, alerts and pop-ups: the cost of computer-initiated interruptions

Responding to computer-initiated notifications requires a shift in attention that disrupts the flow of work. The degree of cost associated with resuming the original task following interruption may be dependent upon such factors as the transition between tasks (was the worker able to consolidate his/her place in the main task before engaging in the interruption?) as well as the nature of the interrupting task itself (e.g., length or complexity). The current paper reviews a number of studies from our laboratory that investigate the effects of brief interruptions to the execution phase of computer-based 5-disk Tower of London problems. The results are interpreted within the theoretical framework of the goal-activation model [1] and suggestions are made for practical applications that may help to minimize the disruption caused.

Decision support and vulnerability to interruption in a dynamic multitasking environment

Using a microworld simulation of maritime decision making, we compared two decision support systems (DSS) in their impact upon recovery from interruption. The Temporal Overview Display (TOD) and Change History Table (CHT) - designed to support temporal awareness and change detection, respectively - have previously proven useful in improving situation awareness; however, evaluation of support tools for multitasking environments should not be limited to the specific aspects of the task that they were designed to augment. Using a combination of performance, self-report, and eye-tracking measures, we find that both DSS counter-intuitively have a negative effect on performance. Resumption lags are increased, elevated post-interruption decision-making times persist for longer, and defensive effectiveness is impaired relative to No-DSS. Eye-tracking measures indicate that in the baseline condition, participants tend to encode the visual display more broadly, where as those in the two DSS conditions may have experienced a degree of attentional tunnelling due to high workload. We suggest that for a support tool to be beneficial it should ease the burden on attentional resources so that these can be used for reconstructing a mental model of the post-interruption scene. We use a maritime microworld to study multitasking and interruption recovery.We use a holistic approach in the assessment of two DSS.We use a combination of performance, self-report and eye tracking measures.Both DSS impair defensive effectiveness and prolong interruption recovery.

Interruptions in the Tower of London Task: Can Preparation Minimise Disruption?:

Responding to computer-initiated notifications requires a shift in attention and therefore disrupts the flow of work. Two exploratory experiments investigate how this decrement can be minimised when a short preparatory time is available before switching to deal with the interrupting task. The execution phase of a computer-based Tower of London task was interrupted by the requirement to perform simple verbal reasoning problems, incurring a cost relative to continuous plan execution. The goal-activation model (Altmann & Trafton, 2002) proposes a critical time period before engaging in the interruption (the “interruption lag”) during which cues pertaining to the primary task can be encoded to facilitate subsequent task resumption. Experiment 1 demonstrated that resumption times were significantly quicker when the interruption was preceded by a three second interruption lag, and that time to complete the interrupting task was also reduced. In Experiment 2, participants chose when to engage in the secondary task. Although this did not benefit task resumption times relative to unexpected interruptions, it significantly reduced completion times on the secondary task. The results are interpreted within the framework of the goal-activation model and suggest that the interruption lag is beneficial in terms of performance on both the primary and interrupting tasks.

Vulnerability to the Irrelevant Sound Effect in Adult ADHD.

Objective: An ecologically valid adaptation of the irrelevant sound effect paradigm was employed to examine the relative roles of short-term memory, selective attention, and sustained attention in ADHD. Method: In all, 32 adults with ADHD and 32 control participants completed a serial recall task in silence or while ignoring irrelevant background sound. Results: Serial recall performance in adults with ADHD was reduced relative to controls in both conditions. The degree of interference due to irrelevant sound was greater for adults with ADHD. Furthermore, a positive correlation was observed between task performance under conditions of irrelevant sound and the extent of attentional problems reported by patients on a clinical symptom scale. Conclusion: The results demonstrate that adults with ADHD exhibit impaired short-term memory and a low resistance to distraction; however, their capacity for sustained attention is preserved as the impact of irrelevant sound diminished over the course of the task.

Memory as discrimination: what distraction reveals

Recalling information involves the process of discriminating between relevant and irrelevant information stored in memory. Not infrequently, the relevant information needs to be selected from among a series of related possibilities. This is likely to be particularly problematic when the irrelevant possibilities not only are temporally or contextually appropriate, but also overlap semantically with the target or targets. Here, we investigate the extent to which purely perceptual features that discriminate between irrelevant and target material can be used to overcome the negative impact of contextual and semantic relatedness. Adopting a distraction paradigm, it is demonstrated that when distractors are interleaved with targets presented either visually (Experiment 1) or auditorily (Experiment 2), a within-modality semantic distraction effect occurs; semantically related distractors impact upon recall more than do unrelated distractors. In the semantically related condition, the number of intrusions in recall is reduced, while the number of correctly recalled targets is simultaneously increased by the presence of perceptual cues to relevance (color features in Experiment 1 or speaker’s gender in Experiment 2). However, as is demonstrated in Experiment 3, even presenting semantically related distractors in a language and a sensory modality (spoken Welsh) distinct from that of the targets (visual English) is insufficient to eliminate false recalls completely or to restore correct recall to levels seen with unrelated distractors . Together, the study shows how semantic and nonsemantic discriminability shape patterns of both erroneous and correct recall.

The LABY Microworld A Platform for Research, Training and System Engineering

The LABY microworld, a functional simulation of Air Traffic Control (ATC), captures the underlying processes involved in electronic air traffic management with a simplified version of the operational human-machine interface. LABY is a computer-based human-in-the-loop dynamic environment whereby a controller must issue directional commands to guide aircraft along a predetermined route, while avoiding potential conflicts and dealing concurrently with other incoming information. It can be used for human factors research or system engineering purposes, or configured specifically for use with expert controllers for the training of non-technical skills in ATC. We present a use case of LABY, comparing the efficiency of input devices for ATC: Input times using the mouse were quicker than with the stylus, but error was not greater. We discuss the potential of LABY for system engineering, training and research purposes.