Why practice reduces dual-task interference.

M. A. Van Selst, E. Ruthruff, and J. C. Johnston (1999) found that practice dramatically reduced dual-task interference in a Psychological Refractory Period (PRP) paradigm with 1 vocal response and 1 manual response. Results from 3 further experiments using the highly trained participants of M. A. Van Selst et al. (1999) support 4 main conclusions: (a) A processing bottleneck exists even after extensive practice; (b) the principal cause of the reduction in PRP interference with practice is shortening of Task 1 bottleneck stages; (c) a secondary cause is that 1 or more, but not all, of the Task 2 substages that are postponed before practice are not postponed after practice (i.e., become automatized); and (d) the extent of PRP reduction with practice depends on the modalities of the 2 responses. A control experiment with 2 manual response tasks showed less PRP reduction with practice than that found by Van Selst et al. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age-related differences and similarities in dual-task interference.

Differences between younger adults (mean age, 20.7 years) and older adults (mean age, 72.7 years) in dual-task performance were examined in 7 experiments in which the overlap between 2 simple tasks was systematically varied. The results were better fit by a task-switching model in which age was assumed to produce generalized slowing than by a shared-capacity model in which age was assumed to reduce processing resources. The functional architecture of task processing appears the same in younger and older adults. There was no evidence for a specific impairment in the ability of older adults to manage simultaneous tasks. There was evidence for both input and output interference, which may be greater in older adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Locus of the single-channel bottleneck in dual-task interference.

Two experiments used the locus-of-cognitive-slack method to determine whether dual-task interference occurs before or after the response selection stage. The experiments used the overlapping tasks paradigm, in which 2 signals, each requiring a different speeded choice response, are presented in rapid succession. In Exp 1, stimulus–response (S–R) compatibility was manipulated by varying whether Task 2 stimuli were mapped onto their responses by a rule or arbitrarily. Compatibility effects were additive with the effects of degree of task overlap, manipulated by varying the stimulus onset asynchrony between the signals. Exp 2 examined 2 additional forms of S–R compatibility: symbolic compatibility (arrows vs letters) and spatial compatibility (the "Simon" effect). Effects of symbolic compatibility were additive with effects of degree of task overlap, whereas the effects of spatial compatibility and degree of task overlap were underadditive. It is argued that only a central-bottleneck model provides a consistent account of these results. The nature of the central bottleneck is considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Process interference and code overlap in dual-task performance.

Perceptual encoding processes have recently been shown to interfere with response selection in dual tasks (P. Jolicoeur & R. Dell'Acqua, 1998). Spatial cross-task compatibility (CTC) was varied to additionally manipulate code overlap across tasks. A new response-cuing paradigm was devised, in which a stimulus movement was used for later report in a perceptual task and a finger movement was used as response in a logically independent reaction task. Three experiments were conducted showing dual-task process interference, but shorter reaction times with CTC than without were also observed. This CTC priming effect was largest with high temporal overlap between the perception and reaction stimuli. The CTC effect was interpreted as resulting from overlap of code activation across tasks, whereas process interference seems to occur to prevent temporal overlap on the level of perceptual encoding and response retrieval processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Graded capacity-sharing in dual-task interference?

Research suggests that dual-task interference is caused by a central bottleneck (together with response grouping and impaired preparation). The emphasis placed on the 1st response in these experiments, however, may have discouraged the sharing of processing resources between tasks. In the present experiment, instructions placed equal emphasis on 2 choice reaction time (RT) tasks in which stimuli were presented simultaneously on 20% of the trials. In contrast to a graded trade-off of resources, a bottleneck predicts bimodality in the distribution of interresponse intervals for the 2 tasks, reflecting the 2 possible orders in which their respective central stages might be performed. Most Ss showed such a bimodality, along with other signs of a bottleneck; the remainder showed evidence of response grouping. Data suggest that the bottleneck is structural rather than strategic and make the graded sharing of resources less plausible. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age differences in dual-task interference are localized to response-generation processes.

Dual-task differences in younger and older adults were explored by presenting 2 simple tasks, with the onset of the 2nd task relative to the 1st task carefully controlled. The possibility of an age-related reduction in the ability to generate and execute 2 similar motor programs was explored by requiring either a manual response to both tasks or a manual response to the 1st and an oral response to the 2nd and was confirmed by the evidence. The age-related interference was greater than would be expected from a general slowing of processing in older adults. The possibility of an age-related reduction in the capacity to process 2 tasks in the same perceptual input modality was explored by presenting both tasks in the visual modality or the 1st task in the auditory modality and the 2nd task in the visual modality and was not supported by the evidence. There was greater interference when both tasks were in the same modality, but it was equivalent for older and younger adults. Age differences in dual-task interference appear quite localized to response-generation processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A demonstration of dual-task performance without interference in some older adults.

Highly efficient dual-task processing is demonstrated when reaction time to each of two tasks does not differ between the dual-task situation and the single-task situation. This has been demonstrated reliably in younger adults; nevertheless, the two extant studies of extensive dual-task training did not find evidence for it in any elderly adult. The origins of age-related differences after training were explored in a study in which the stimuli for the two tasks were perfectly redundant although two distinct responses were required. The dual-task situation thus greatly reduced the demands of stimulus categorization while still requiring two response selections and two response executions. After only limited training 8 of 8 younger adults and 5 of 8 older adults showed performance consistent with highly efficient processing. Three older adults failed to show this even after 12 training sessions. The results implicate stimulus categorization more than response selection as an important locus of inefficient dual-task processing, particularly for older adults. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The locus of dual-task interference: Psychological refractory effects on movement-related brain potentials.

Sought to measure the motor potentials for each of 2 concurrent tasks and to use these measurements to identify the locus of dual-task interference. Lateralized readiness potentials (LRPs) were measured in the psychological refractory period paradigm, in which a separate response is required to each of 2 successive signals. As the interval between the signals decreased, the 2 reaction time (RT) tasks increasingly overlapped and the 2nd RT was prolonged. The LRP for the 2nd task was also delayed but maintained a constant temporal relation with the 2nd RT and sometimes preceded the 1st-task RT. The results indicate that (1) independent measures of the LRP can be obtained for each of 2 concurrent tasks, (2) slowing of the 2nd task was caused by a delay in processes that precede LRP onset, and (3) the 1st task may cease to interfere with the 2nd considerably before producing an overt response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attention, gaze shifting, and dual-task interference from phonological encoding in spoken word planning.

Controversy exists about whether dual-task interference from word planning reflects structural bottleneck or attentional control factors. Here, participants named pictures whose names could or could not be phonologically prepared, and they manually responded to arrows presented away from (Experiment 1), or superimposed onto, the pictures (Experiments 2 and 3); or they responded to tones (Experiment 4). Pictures and arrows/tones were presented at stimulus onset asynchronies of 0, 300, and 1,000 ms. Earlier research showed that vocal responding hampers auditory perception, which predicts earlier shifts of attention to the tones than to the arrows. Word planning yielded dual-task interference. Phonological preparation reduced the latencies of picture naming and gaze shifting. The preparation benefit was propagated into the latencies of the manual responses to the arrows but not to the tones. The malleability of the interference supports the attentional control account. This conclusion was corroborated by computer simulations showing that an extension of WEAVER++ (A. Roelofs, 2003) with assumptions about the attentional control of tasks quantitatively accounts for the latencies of vocal responding, gaze shifting, and manual responding. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A dual-task study of interference between mental activity and control of balance

OBJECTIVE: This study aimed to examine interference between mental activity and control of balance. STUDY DESIGN: In a mixed design, dual-task study, the performance of patients and healthy control subjects was compared on computerized dynamic posturography, on a visuospatial mental task, and when performing the mental task while balancing. SETTING: The study was performed at a tertiary referral outpatient neuro-otology clinic. PATIENTS AND SUBJECTS: The patient group comprised 24 patients seen consecutively at the clinic because of vertigo and dizziness. The control group consisted of 24 subjects with no complaint or medical history of dizziness or balance disorder, matched with the patients for age and gender. MAIN OUTCOME MEASURES: Performance on a visuospatial mental task and on the computerized dynamic posturography test (conditions 4 and 5) was measured. RESULTS: Balancing on the posturography test resulted in a deterioration in performance on the mental task for both patients and control subjects. The effect was more marked when subjects had their eyes closed. Results on the balance test showed that normal subjects and patients with normal balance also swayed more when performing the mental task, whereas patients who had failed the posturography test swayed less when performing the mental task. CONCLUSIONS: These results show that mental performance deteriorates when performing a demanding balance task. In addition, in both normal subjects and patients, balance also may be affected by mental activity in complex and varied ways that merit further investigation.     

Role conflict and symptoms of psychological distress in college-educated women.

Studied sex role attitudes, need for achievement, and employment patterns of 136 women's college graduates out of college 10 yrs and 132 out of college 25 yrs in relation to symptoms of mental illness using a 3-wave mail questionnaire technique. Questionnaire returns totaled 71% of the selected sample and established validity of the Twenty-Two Item Screening Score in mail questionnaire studies. Neither employment status nor achievement motivation, assessed by stories written in response to verbal cues, were significantly related to symptom scores. However, Ss with contemporary sex role orientations, as indicated by the Revised Fand Inventory, exhibited significantly higher symptom scores. Also, the class out of college 10 yrs had significantly more members (a) with high need for achievement, (b) with contemporary sex role orientation, and (c) who had advanced degrees and were earning higher incomes. They also had significantly higher symptom scores. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role conflict in forensic clinical psychology: Reply to Arcaya.

I agree with Arcaya that there is potential for serious role conflict in conducting forensic evaluations, but I disagree with how this problem is characterized and explained. Arcaya's contentions are reformulated as research hypotheses that can be empirically tested. The American Psychological Association's Ethical Principles of Psychologists are relevant and are cited in support of several proposals for safeguarding defendant rights and reducing the potential for role conflict in forensic evaluations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of interference in retention by rats with hippocampal lesions.

Studied involvement of the hippocampus in memory in 22 male albino Sprague-Dawley rats by employing a retention task with and without interpolated activity. Ss with extensive damage to hippocampus were able to relearn a preoperatively acquired single-alternation task with savings and to perform the single alternation with relatively long delays at a level similar to that of control Ss. However, hippocampals were more affected than normals by an interpolated activity that interferes with retention. The finding of normal retention combined with increased susceptibility to interference supports the view that the memory impairment in Ss with damage to hippocampus may be due to an excess of interference among stored information. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age differences in dual-task performance after practice.

This study investigated whether older adults could acquire the ability to perform 2 cognitive operations in parallel in a paradigm in which young adults had been shown to be able to do so (K. Oberauer & R. Kliegl, 2004). Twelve young and 12 older adults practiced a numerical and a visuospatial continuous memory updating task in single-task and dual-task conditions for 16 to 24 sessions. After practice, 9 young adults were able to process the 2 tasks without dual-task costs, but none of the older adults had reached the criterion of parallel processing. The results suggest a qualitative difference between young and older adults in how they approach dual-task situations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Executive control of visual attention in dual-task situations.

A theory of executive control is presented that proposes that executive processes control subordinate processes by manipulating their parameters, reconfiguring them to respond in accord with the current task set. It adopts C. Bundesen's (1990) theory of visual attention (TVA) and R. M. Nosofsky and T. J. Palmeri's (1997) exemplar-based random walk (EBRW) as the theory of subordinate processes. It assumes that a task set is a set of TVA and EBRW parameters sufficient to perform a task and that set switching involves changing those parameters. The theory solves 2 computational problems that emerge in dual-task situations. the binding problem and the serial order problem. It can perform dual tasks in series or in parallel but prefers the serial strategy because it is faster and it solves the binding problem naturally. The theory accounts for concurrence cost, set-switching cost, crosstalk between tasks, and the modulation of crosstalk by task set. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive resources and dual-task interference effects at retrieval in normal people: The role of the frontal lobes and medial temporal cortex.

Conducted 3 experiments to examine the hypothesis that concurrent secondary tasks at retrieval will interfere more with long-term, episodic memory functions involving the frontal lobes than those involving the medial temporal lobes hippocampus (MTL/H). The rationale is that strategic retrieval processes mediated by the frontal lobes place greater demands on cognitive resources than do relatively automatic associative retrieval processes (ecphory) mediated by the temporal lobes. In Exps 1 and 2, sequential finger tapping was performed at encoding, at retrieval, at both, or at neither. Recall of a categorized list of 16 words from the California Verbal Learning Test in Exp 1, and release from proactive inhibition (PI) in Exp 2, both being tests that involve the frontal lobes, were impaired if normal Ss tapped at both encoding and retrieval. Concurrent tapping had little effect on rate of learning in Exp 1 and on total words recalled during the buildup of PI in Exp 2, both of which are indices that are affected more by MTL/H than by frontal lesions. In Exp 3, tapping by normal Ss affected letter fluency, a test more sensitive to frontal lobe than temporal lobe damage, but not category fluency, for which the reverse is true. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nitrogen narcosis measured by dual-task performance.

Two hyperbaric studies tested detrimental effects of 188-ft sea water gauge (fswg) air pressure. In each experiment, 8 males aged 22–32 yrs, qualified for hyperbaric exposures, executed single-task controls of a choice reaction time (RT) task and a pursuit tracking task, as well as their dual-task combinations. All tasks were tested 0, 10, and 188 fswg. Exp I was designed to measure the effects of nitrogen narcosis on 2 successive weekly dives. No improvement specific to the 188 fswg depth was found on the 2nd dive. It is concluded that the prior exposure did not result in measurable adaptation to narcosis. At 188 fswg, the rate of information transmission in the choice RT task was slowed and tracking error increased. Dual-task requirements resulted in poorer tracking but left choice RT performance unaffected. In Exp II, half of the Ss stopped at 19 fswg before proceeding to depth. They showed a decrement in performance at 188 fswg equal to, or greater than, that found for the remaining Ss, who used the standard procedure of descending to depth directly. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Resolving decisional conflict by Gestalt two-chair dialogue: Relating process to outcome.

31 clients (aged 17–65 yrs) completed a 6-wk program using Gestalt 2-chair dialog to work on intrapsychic conflict related to the making of a decision. Ss were classified as resolvers or nonresolvers based on a pattern of in-session process indicators. Resolvers were those Ss who had manifested 3 components of a proposed model of conflict resolution: the expression of criticism by one part of the personality, the expression of feeling and wants by another, and the softening in attitude of the "critic." These attributes were measured in terms of voice quality, depth of experience, and structural analysis of social behavior. Resolvers were significantly less undecided and less anxious after treatment and reported greater improvement on target complaints and behavior change. In addition, after the session in which the "critic" softened, resolvers reported greater conflict resolution, less discomfort, greater mood change, and greater goal attainment than nonresolvers. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Automatic stimulus–response translation in dual-task performance.

In bottleneck models of overlapping-task performance, stimulus-response translation for secondary tasks is postponed until the primary response is selected. If this is so, then compatibility between the secondary and primary responses, or between the secondary response and the primary stimulus, should not affect primary-task performance. Yet such effects were demonstrated in 5 dual-task experiments combining primary manual and secondary vocal tasks: Pronounced effects of compatibility between the secondary and primary response and between the secondary response and primary stimulus were found on primary-task performance. The latter effect was also found with the lowest level of an extensive stimulus onset asynchrony variation, when the secondary task was not speeded, and even when the 2 tasks were performed on different trials. Findings suggest that secondary responses were activated before primary response selection was completed and thus support an automatic-translation hypothesis holding that, although eventual response selection may be serial, stimulus-response translation is performed in parallel. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Concurrent validation of a dual-task selection test.

Examined individual differences in dual-task decrement within the framework of a concurrent validation paradigm. The performance of 49 males employed as detection and communication equipment operators aboard military antisubmarine aircraft was measured in a dual-task situation, which combined a visual decision task and an auditory short-term memory task. Criterion scores from a standardized exercise in a radar training simulator were not significantly related to dual-task measures. Peer ratings, supervisor rank orderings based on flight performance, radar training grades, and indexes combining subjective and objective criteria were significantly related to dual-task measures. The dual-task measures, when combined with predictive measures available from aircrew selection tests, enhanced the potential predictive effectiveness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)