Travis L. Seymour

Virtually Perfect Time Sharing in Dual-Task Performance: Uncorking the Central Cognitive Bottleneck

A fundamental issue for psychological science concerns the extent to which people can simultaneously perform two perceptual-motor tasks. Some theorists have hypothesized that such dual-task performance is severely and persistently constrained by a central cognitive “bottleneck,” whereas others have hypothesized that skilled procedural decision making and response selection for two or more tasks can proceed at the same time under adaptive executive control. The three experiments reported here support this latter hypothesis. Their results show that after relatively modest amounts of practice, at least some participants achieve virtually perfect time sharing in the dual-task performance of basic choice reaction tasks. The results also show that observed interference between tasks can be modulated by instructions about differential task priorities and personal preferences for daring (concurrent) or cautious (successive) scheduling of tasks. Given this outcome, future research should investigate exactly when and how such sophisticated skills in dual-task performance are acquired.

Theoretical implications of articulatory duration, phonological similarity, and phonological complexity in verbal working memory.

The phonological-loop model provides a prominent theoretical description of verbal working memory. According to it, serial recall accuracy should be inversely related to the articulatory duration and phonological similarity of verbal items in memorized sequences. Initial tests of these predictions by A. D. Baddeley and colleagues (e.g., A. D. Baddeley, N. Thomson, & M. Buchanan, 1975) appeared to support the phonological-loop model, but subsequent researchers have obtained conflicting data that putatively disconfirm its assumptions. Such conflicts may have stemmed from less than ideal measurements of articulatory duration and phonological similarity. This article discusses these concerns and proposes new theoretically principled methods for measuring articulatory duration and phonological similarity. Two experiments that used these methods in the context of a verbal serial recall task are reported. The results of these experiments confirm and extend the predictions of the phonological-loop model while disarming previous criticisms of it.

Models of Working Memory: Insights into Working Memory from the Perspective of the EPIC Architecture for Modeling Skilled Perceptual-Motor and Cognitive Human Performance

Abstract : Computational modeling of human perceptual-motor and cognitive performance based on a comprehensive detailed information- processing architecture leads to new insights about the components of working memory. To illustrate how such insights can be achieved a precise production system model that uses verbal working memory for performing a serial memory-span task through a strategic phonological loop has been constructed with the Executive-Process/ Interactive-Control (EPIC) architecture of Kieras and Meyer. The model accounts well for empirical results from representative memory-span studies The success of this account stems from five central features of EPIC that may be compared and contrasted with those of other currently popular alternative theoretical frameworks.

Executive-process interactive control: A unified computational theory for answering 20 questions (and more) about cognitive ageing

Although the effects of ageing on human information processing and performance have been studied extensively, many fundamental questions about cognitive ageing remain to be answered definitively. For example, what are the sources of age-related slowing? How much is working-memory capacity reduced in older adults? Is time-sharing ability lost with age? Answering such questions requires a unified computational theory that characterises the interactive operations of many component mental processes and integrates diverse data on cognitive ageing. Toward fulfilling this requirement, an executive-process interactive control (EPIC) architecture has been extended to model performance of both young and older adults. EPIC models yield accurate accounts of ageing effects on reaction times and accuracy in basic dual-task and working-memory paradigms. From these accounts, it appears that time-sharing ability and working-memory capacity decrease relatively little until after 70 years of age. Before age 70, at least som...

Electromyographic evidence for response conflict in the exclude recognition task.

How do memory retrieval processes lead to overt responses in strategic recognition tasks (responding “old” to one class of familiar stimulus and “new” to another)? Many current theories of memory retrieval ignore the response requirements in such memory tasks, instead modeling them using memory processes (e.g., familiarity and recollection) alone (see Yonelinas, 2002). We argue that strategic recognition involves conflict in response processing similar to canonical conflict tasks (e.g., the Stroop task). The parallel task set (PTS) model (Seymour, 2001) accounts for performance in strategic recognition tasks (e.g., the exclude recognition task) by suggesting that motor response conflict occurs when one responds “new” to familiar stimuli. We tested this prediction using surface electromyography, a measure incontrovertibly related to motor execution. Overall, results are consistent with the PTS model’s assumption that recognition, motor, and control processes interact in strategic retrieval tasks. The implications of these data for models of memory retrieval and response conflict are discussed.

Brain activation evidence for response conflict in the exclude recognition task

How do memory retrieval processes (i.e., familiarity and recollection processes) interact with motor and control processes to bring about an appropriate response? Our parallel task-set model predicts, and behavioral and electromyographic data support, the hypothesis that under some circumstances familiarity and recollection processes activate competing responses. Combining predictions from the parallel task-set model and the conflict monitoring hypothesis, this competition should lead to response conflict and corresponding activity in anterior cingulate cortex (ACC). However, ACC activity in response to competing familiarity and recollection retrieval processes is inconsistently reported in the literature. We tested this prediction directly by measuring brain activation with functional magnetic resonance imaging while participants performed an exclude recognition task (i.e., respond one way to one set of familiar stimuli and another way to new and to a different set of familiar stimuli). As predicted by our model, overriding a familiarity-based response led to increased activity in ACC. These data suggest that recognition, motor, and control processes interact in strategic retrieval tasks.

Combining blink, pupil, and response time measures in a concealed knowledge test.

The response time (RT) based Concealed Knowledge Test (CKT) has been shown to accurately detect participants’ knowledge of mock-crime-related information. Tests based on ocular measures such as pupil-size and blink-rate have sometimes resulted in poor classification, or lacked detailed classification analyses. The present study examines the fitness of multiple pupil and blink related responses in the CKT paradigm. To maximize classification efficiency, participants’ concealed knowledge was assessed using both individual test measures and combinations of test measures. Results show that individual pupil-size, pupil-slope, and pre-response blink-rate measures produce efficient classifications. Combining pupil and blink measures yielded more accuracy classifications than individual ocular measures. Although RT-based tests proved efficient, combining RT with ocular measures had little incremental benefit. It is argued that covertly assessing ocular measures during RT-based tests may guard against effective countermeasure use in applied settings. A compound classification procedure was used to categorize individual participants and yielded high hit rates and low false-alarm rates without the need for adjustments between test paradigms and subject populations. We conclude that with appropriate test paradigms and classification analyses, ocular measures may prove as effective as other indices, though additional research is needed.

Full length articleAchieving the performance benefits of hands-on experience when using digital devices: A representational approach

Digital devices have become ubiquitous fixtures in classrooms nationwide. Despite this rapid incorporation of tablet computers in educational settings, the costs and benefits of digitization are understudied. Prior research shows that reading comprehension tends to be best in physical rather than digital modalities. The current study extends these findings to physical and digital versions of spatial tasks. Participants engaged in a physical or digital tangram task and demonstrated significant performance differences in both accuracy and response time. Later, on a timed math test, participants solved more problems correctly and solved each problem more quickly if physical manipulatives, rather than a digital interface, were used in the tangram task. Two follow-up experiments showed that these performance differences are not due to interactional limitations of the tablet, but are instead likely driven by representational differences. These results show that priming physical representations of spatial tasks can reduce the digital task performance deficit. Physical interaction with tangrams yields spatial and math performance benefits.Benefits of physical interaction are not obtained with an analogous digital task.Interactional limitations do not account for interface-based performance differences.Spatial and math performance differences are mitigated by representational priming.

Achieving the performance benefits of hands-on experience when using digital devices

Digital devices have become ubiquitous fixtures in classrooms nationwide. Despite this rapid incorporation of tablet computers in educational settings, the costs and benefits of digitization are understudied. Prior research shows that reading comprehension tends to be best in physical rather than digital modalities. The current study extends these findings to physical and digital versions of spatial tasks. Participants engaged in a physical or digital tangram task and demonstrated significant performance differences in both accuracy and response time. Later, on a timed math test, participants solved more problems correctly and solved each problem more quickly if physical manipulatives, rather than a digital interface, were used in the tangram task. Two follow-up experiments showed that these performance differences are not due to interactional limitations of the tablet, but are instead likely driven by representational differences. These results show that priming physical representations of spatial tasks can reduce the digital task performance deficit. Physical interaction with tangrams yields spatial and math performance benefits.Benefits of physical interaction are not obtained with an analogous digital task.Interactional limitations do not account for interface-based performance differences.Spatial and math performance differences are mitigated by representational priming.