Task Switching Over the Lifespan

People often switch from one goal to another, in response to changing environmental demands. Task switching affords flexibility, but at a price. A robust switch cost ensues, whereby individuals are slower and less accurate when switching between tasks than when repeating tasks. The current dissertation investigated the factors that contribute to a switch cost, using an exceptionally large sample of over 25,000 individuals (ages 10 to over 65) collected online. Switch costs are interpreted as the duration of psychological processes that are recruited to shift between tasks. In Study 1, shifting a task took 576 ms (or 108%) longer than performing a single task. Shifting tasks resulted in a 34% immediate decrease in productivity. An additional 74% long-term decrease in productivity occurred from maintaining readiness for a shift, and for using a cue to select a task, both of which occur even without an actual shift taking place. The results show that the seemingly simple switch cost involves multiple processes. Understanding these processes is crucial to interpret how flexibility varies with age. In Study 2A, task switching process developed until adulthood and then declined, similar to general cognitive ability. However, each process changed differently with age. Findings show that decline is not simply development in reverse: The rate of decline in mid to late adulthood was up to 20 times slower than the rapid development in adolescence; Middle-aged adults were slower than young adults, but as accurate; They maintained less advance readiness but used contextual cues as well as their younger counterparts. In Study 2B, the effects of age were replicated in an independent sample using identical methodology. These findings highlight the usefulness of web-based data collection, effect size estimation, and segmented regression techniques

Effects of non-pharmacological or pharmacological interventions on cognition and brain plasticity of aging individuals.

Brain aging and aging-related neurodegenerative disorders are major health challenges faced by modern societies. Brain aging is associated with cognitive and functional decline and represents the favourable background for the onset and development of dementia. Brain aging is associated with early and subtle anatomo-functional physiological changes that often precede the appearance of clinical signs of cognitive decline. Neuroimaging approaches unveiled the functional correlates of these alterations and helped in the identification of therapeutic targets that can be potentially useful in counteracting age-dependent cognitive decline. A growing body of evidence supports the notion that cognitive stimulation and aerobic training can preserve and enhance operational skills in elderly individuals as well as reduce the incidence of dementia. This review aims at providing an extensive and critical overview of the most recent data that support the efficacy of non-pharmacological and pharmacological interventions aimed at enhancing cognition and brain plasticity in healthy elderly individuals as well as delaying the cognitive decline associated with dementia

Guarded Play: Multi-Tasking in Parent-Child Interactions

This brief analysis utilizes a CA perspective to deepen our understanding of the ways in which participants in interactions are able to handle more than one activity simultaneously. Many of the studies on multi-tasking, as Good (2009) noted, address this from a cognitive science perspective (e.g. Salvucci, 2005; Salvucci, Taatgen, & Kushleyeva, 2006), focusing on the brain’s ability to attend to several tasks at once. According to this work, we humans do a less than stellar job at balancing more than one thing at a time. In fact, with each task we add to the mix, our performance suffers that much more. As a social scientist, I find these conclusions enlightening and worthy of further study. As a mother, I chuckle, because even as I write this, my ear is bent to my daughter doing homework and the dinner that is on the stove, and I have gotten up from my workstation twice to wipe the bedroom wall clean of all traces of marker from my son’s dirty hands. Since at the end of the day, every member of my family is fed, cleaned, and accounted for, I proclaim that I do my job successfully. Thus, I agree wholeheartedly with the argument (Good, 2009) that by looking at the social action of multi-tasking as it happens in real time, as it happens so many nights in the lives of families, we might complicate the notion that it is something that humans simply cannot do well

Cognitive Control in Verbal Task Switching

Task switching produces a number of reliable behavioural measures, the main focus of interest here being ‘switch cost’, the increase in response time when switching between tasks as opposed to performing them separately. Switch costs are typically measured between two tasks and compared to a single-task repeat condition. Current explanations of switch cost fall broadly into either active reconfiguration based accounts (e.g. Rogers & Monsell, 1995) whereby the extra time taken to switch between tasks is attributable to reconfiguration of task set, or passive carryover accounts (Allport, Styles & Hsieh, 1994) where extra time is accrued by the need to overcome conflict between the current task set and the enduring activity of the previous task set. This thesis used the Continuous Series II (Gurd, 1995), a novel continuous verbal switching task which requires individuals to switch continuously between increasing numbers of overlearned sequences (e.g. days, numbers). The aim was to investigate the application of general (whole-task) switch costs (RT costs), memory-based switching and the differential pattern of errors produced by the task, with a view to determining the most appropriate theoretical model to explain costs in the task. General switch costs are measured over the whole time course of the task from beginning to end, instead of the more usual measurement of switch cost over a single switch or repeat within the whole task. Such long-term measures of switch cost account for ‘global representational structures’ in the task, which are said to contribute to the cost of switching yet are absent from local transitional measures (Kleinsorge, Heuer & Schmidtke, 2004). Global representational structures account for not only the current and preceding trials actually performed but also the possible alternatives for the preceding, current and subsequent trials, thereby reflecting all representations relating to performance of the tasks. The Continuous Series II (Gurd, 1995) measures costs continuously over time between increasing numbers of verbal tasks and as yet has not been linked to either a reconfiguration or carryover-based account. Initial administration to healthy controls and neurological patients confirmed difficulty-related increasing costs and revealed a dissociation of errors between two versions of the task, one including semantic categories. This suggested differential sources of control overseeing conflict detection and resolution, linked in this work to Kahneman’s dual system model (Kahneman, 2011) and suggesting the implication of active control. Further work with monozygotic twins mirrored for handedness revealed no predicted effect of handedness but did reveal the employment of vocalised inner-speech as a successful self cueing device, known to be supportive of active reconfiguration in switching (Monsell, 2005). Such cueing was employed by this sample of older adults but had not appeared to benefit the neurological patients who clearly had reconfiguration deficits. Further development of the two versions of the task also allowed rejection of a passive carryover explanation of switch-cost on the basis that switching to the easier task was not more difficult, counter to the prediction of Allport, Styles & Hsieh (1994). At this stage it was evident that some portion of general cost for the task may be artefactual, as participants displayed behaviour suggesting the order of tasks and their updating nature (task content) may be inflating cost beyond a pure measure of switching (an inevitable risk of general switch cost measurement). Investigation of task order showed that production of the category ‘days’ appeared to conflate sources of error. Reducing the difficultly of component tasks (removing the need to update items) demonstrated that a substantial proportion of general cost was indeed purely switch-related. Returning to the question of cueing (previously demonstrated to be beneficial when self-generated), the final study introduced explicit external cues, consistently predicted to benefit switching (Monsell, 2005). These cues did not reduce time costs in verbal task switching and furthermore failed to prevent errors of task order. The lack of external cue benefit supports an amended version of the Rogers & Monsell (1995) task-set reconfiguration model as the best explanation of switch costs in verbal task-switching. This amended model relies entirely on internally generated representations in a closed system and supports the role of active control in generating switch-cost. General cost, while incorporating task-related artefacts, rehearsals and error recovery, nevertheless has at its core a switch related element. Furthermore, the failure of cues to extinguish between-task errors negates excessive reliance on working memory and further supports the rejection of passive carryover accounts of task switch cost

Switch choice in applied multi-task management

2014 Summer.Little to date is known concerning how operators make choices in environments where cognitive load is high and they are faced with multiple different tasks to choose from. This dissertation reviewed a large body of voluntary task switching literature concerning basic research into choice in task switching, as well as what literature was available for applied task switching. From this and a prior model, a revised model of task switching choice that takes into account specific task attributes of difficulty, priority, interest and salience, was developed. In the first experiment, it was shown that task difficulty and priority influenced switching behavior. While task attributes were hypothesized to influence switching, a second major influence is time on task. In the second experiment, it was shown that tasks indeed vary in their interruptability over time, and this was related in part to what task was competing for attention as well as the cognitive processing required for the ongoing task performance. In a third experiment, a new methodology was developed to experimentally assess the role of diminishing rate of returns for performing a task. This declining rate was expected (and did result in) a general increase of switching away from an ongoing task over time. In conclusion, while task attributes and time on task play a major role in task switching in the current studies, defining the time period for theorized effects appears to be the next major step toward understanding switching choice behavior. Additionally, though the experiments are novel and certainly make a major contribution, to the extent that behavior is only represented in them, the methodology may miss some amount of `other' task behavior, such as visual sampling

Queuing Network Modeling of Human Multitask Performance and its Application to Usability Testing of In-Vehicle Infotainment Systems.

Human performance of a primary continuous task (e.g., steering a vehicle) and a secondary discrete task (e.g., tuning radio stations) simultaneously is a common scenario in many domains. It is of great importance to have a good understanding of the mechanisms of human multitasking behavior in order to design the task environments and user interfaces (UIs) that facilitate human performance and minimize potential safety hazards. In this dissertation I investigated and modeled human multitask performance with a vehicle-steering task and several typical in-vehicle secondary tasks. Two experiments were conducted to investigate how various display designs and control modules affect the driver's eye glance behavior and performance. A computational model based on the cognitive architecture of Queuing Network-Model Human Processor (QN-MHP) was built to account for the experiment findings. In contrast to most existing studies that focus on visual search in single task situations, this dissertation employed experimental work that investigates visual search in multitask situations. A modeling mechanism for flexible task activation (rather than strict serial activations) was developed to allow the activation of a task component to be based on the completion status of other task components. A task switching scheme was built to model the time-sharing nature of multitasking. These extensions offer new theoretical insights into visual search in multitask situations and enable the model to simulate parallel processing both within one task and among multiple tasks. The validation results show that the model could account for the observed performance differences from the empirical data. Based on this model, a computer-aided engineering toolkit was developed that allows the UI designers to make quantitative prediction of the usability of design concepts and prototypes. Scientifically, the results of this dissertation research offer additional insights into the mechanisms of human multitask performance. From the engineering application and practical value perspective, the new modeling mechanism and the new toolkit have advantages over the traditional usability testing methods with human subjects by enabling the UI designers to explore a larger design space and address usability issues at the early design stages with lower cost both in time and manpower.PHDIndustrial and Operations EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/113590/1/fredfeng_1.pd

Producing effective messages in the multicommunicating environment managing multitasking in organizational meetings

At some time during a week a corporate worker is likely to attend an organizational meeting. The availability of multiple wireless technologies makes it possible for meeting attendees to be engaged in multitasking, i.e., performing multiple tasks simultaneously. During meetings the attendees often take the opportunity to continue working on their projects, read and write e-mail messages or surf the Web. This study evaluated the impacts of such multitasking behaviors on individual performances in the multicommunicating environment. The study used the experimental design. Respondents for this study were 154 undergraduate students in a large southeastern university. The participants accomplished two communication tasks simultaneously during the experiment: listening and writing. They were instructed to listen to a lecture presentation and at the same time write responses to an open-ended online survey questions, i.e., the participants of the study were multitasking.The researcher compared several factors (social presence, multitasking abilities, polychronicity, task prioritization, and receiver apprehension) for three different treatments (multi task vs. single task, live presenter vs. virtual presenter, one channel vs. two channels). In addition, a scale to measure multitasking abilities was developed and validated during the experiment. It was found that multitasking or completing two tasks simultaneously significantly decreases performances on both tasks. The performance on the listening task was decreased by 9.5%; the writing task performance was decreased by 11.2%. The researcher found no evidence that the degree of social presence could affect task prioritization and performance in the multicommunicating environment. However, multi-task performance was improved in the two-channel condition. Presenting the information in visual and oral forms significantly enhanced the information recall on the listening task.This finding suggests that the negative impact of multitasking can be reduced under certain conditions. The results of the study also indicate that individuals differ in their abilities to multitask. It was found that the level of receiver apprehension affects not only processing outcomes as message information is being received and perceived, but also processing outcomes as message information is being produced. It seems relatively clear that being less apprehensive about listening is an index of better performance in the multicommunicating environment

Subjective estimates of total processing time in dual-tasking: (some) good news for bad introspection

Previous studies have shown severe distortions of introspection about dual-task interference in the Psychological Refractory Period (PRP) paradigm. The present study investigated participants’ ability to introspect about the total trial time in this paradigm, as this temporal information may arguably be more relevant for strategic task scheduling than subjective estimates of each task within the dual task. To this end, participants provided estimates of their reaction times (IRTs) for the two subtasks in one half of the experiment, and estimates of the total trial time (ITTs) in the other half of the experiment. Although the IRT results showed the typical unawareness of the PRP effect, ITTs reflected the effects of SOA and Task 2 difficulty on objective total trial time. Additional analyses showed that IRTs were influenced by the introspective task order; that is, the ITT pattern carried over to IRTs when IRTs were assessed in the second half of the experiment. Overall, the present results show that people are able to accurately introspect about total trial time in the PRP paradigm and thus provide some good news for bad introspection in the PRP paradigm

Exploring the Aetiology and Effects of Pharmacological Cognitive Enhancement use in UK University Students.

Media claims suggest that use of pharmacological cognitive enhancers (PCE) in UK universities is significant and is increasing, though academic research has come to less consistent conclusions. While there has been expansion of research in this area, the public health impact of long-term PCE use, including the potential for adverse effects to cognitive, neurological and physiological functioning remains unclear. Consequently, this thesis aimed to investigate the aetiology and long-term effects of PCE use in some UK universities. Study 1 aimed to investigate CE use in four UK universities, including: which substances are commonly used, the reasons for use and which factors relate to consumption. Here, caffeinated products were the most popular, followed by modafinil. Furthermore, several sociodemographic and personality variables were part of a statistical model to predict CE use, although only gender, age and moral perceptions of modafinil use were found to be significant. Study 2 focussed on modafinil as the most popular PCE aiming to assess the long-term impact (> 3 months) of use on executive functioning by administering various cognitive performance measures. Despite no behavioural differences on the 2-back (working memory) and the continuous performance task (sustained attention), modafinil users responded to both horizontal and vertical cues more quickly than nonusers on the cued go/no-go task (inhibitory control) without experiencing an accuracy trade-off or performance decrement. To investigate the neural substrates of any potential cognitive deficits, Study 3 assessed cognitive and neurophysiological processes by using functional near-infrared spectroscopy, electrocardiogram and a digital sphygmomanometer alongside cognitive performance measures designed to increase cognitive workload. It was found that there were no behavioural performance differences on easy and difficult variants of the multitasking framework (stressor) or 3-back (working memory) between groups, but users experienced significantly lower systolic blood pressure across the tasks and greater haemodynamic change during the 3-back. Blood pressure indicated that users appeared 11 | P a g e less physiologically aroused during performance measures, but increased haemodynamic response compared with controls revealed possible underlying cognitive deficits. Taken as a whole, modafinil appears to be the most popular PCE in the UK for university students, and long-term use unexpectedly revealed enhanced inhibitory control but possible deficits to working memory performance. This research consolidates previous claims about modafinil as the most popular PCE among UK university students. Furthermore, this is the first study to investigate long-term modafinil use and establish behavioural and neurophysiological differences with nonusers