Sex differences in dual-task interference between speaking and a manual force-production task

12 male and 12 female right-handed adults performed a unimanual force-production task alone and while sound-shadowing high frequency words. The secondary speech task disrupted right-hand performance by men and left-hand performance by women. The implications of these findings for intrahemisphere-interference models of dual-task performance are discussed.     

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.     

Sex differences in object location memory and spatial navigation in Long-Evans rats

In both humans and rodents, males typically excel on a number of tasks requiring spatial ability. However, human females exhibit advantages in memory for the spatial location of objects. This study investigated whether rats would exhibit similar sex differences on a task of object location memory (OLM) and on the watermaze (WM). We predicted that females should outperform males on the OLM task and that males should outperform females on the WM. To control for possible effects of housing environment, rats were housed in either complex environments or in standard shoebox housing. Eighty Long-Evans rats (40 males and 40 females) were housed in either complex (Complex rats) or standard shoebox housing (Control rats). Results indicated that males had superior performance on the WM, whereas females outperformed males on the OLM task, regardless of housing environment. As these sex differences cannot be easily attributed to differences in cognitive style related to linguistic processing of environmental features or to selection pressures related to the hunting gathering evolutionary prehistory of humans, these data suggest that sex differences in spatial ability may be related to traits selected for by polygynous mating strategies.     

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.     

Sex differences in navigation strategy and efficiency

Research on human navigation has indicated that males and females differ in self-reported navigation strategy as well as objective measures of navigation efficiency. In two experiments, we investigated sex differences in navigation strategy and efficiency using an objective measure of strategy, the dual-solution paradigm (DSP; Marchette, Bakker, & Shelton, 2011). Although navigation by shortcuts and learned routes were the primary strategies used in both experiments, as in previous research on the DSP, individuals also utilized route reversals and sometimes found the goal location as a result of wandering. Importantly, sex differences were found in measures of both route selection and navigation efficiency. In particular, males were more likely to take shortcuts and reached their goal location faster than females, while females were more likely to follow learned routes and wander. Self-report measures of strategy were only weakly correlated with objective measures of strategy, casting doubt on their usefulness. This research indicates that the sex difference in navigation efficiency is large, and only partially related to an individual’s navigation strategy as measured by the dual-solution paradigm.     

Sex differences in spatial ability and spatial activities

Explanations of sex-related differences in spatial ability emphasizing the role of sex-differentiated experience have not been supported by direct measurement of spatial activities during adolescence, the period when these differences seem to increase. The present research involved development of a scale to measure the spatial experience of adolescents and adults. In Study 1, a list, as complete as possible of adolescent activities was compiled and given to undergraduate judges for ratings of involvement of spatial skills and sex-typing. Judges also indicated whether they had participated in each activity. Activities considered spatial by 75% or more of the judges were used to develop a spatial experience questionnaire. Judgments of the spatial nature of tasks were positively correlated with judged masculinity and with greater male than female participation. In Study 2, participation in spatial activities by undergraduates was correlated with spatial ability as measured by the Differential Aptitude Test. The activity questionnaire should prove useful in studying the development of spatial ability in adolescents and adults.     

Quantitative and qualitative sex differences in spatial navigation

We examined sex differences in spatial navigation performance using an ecologically relevant experimental paradigm in which virtual maze-like museums are projected in front of a treadmill. Thirty-two 20-30-year-old adults (16 women/16 men) performed a way-finding task in city-block (straight corridors) or variable (irregular corridors) topographies while walking on the treadmill. Sex differences in spatial navigation performance were reduced in variable topographies, suggesting less reliance on spatial relational learning among women. Also, spatial geometric knowledge of the mazes continued to be higher in men after all participants had attained perfect place-finding performance. Results indicate that sex differences in spatial navigation performance are modulated by interactions between environmental demands and sex differences in spatial processing.     

Role of outcome conflict in dual-task interference

The traditional explanation for dual-task interference is that tasks compete for scarce processing resources. Another possible explanation is that the outcome of the processing required for one task conflicts with the processing required for the other task (e.g., cross talk). To explore the contribution of outcome conflict to task interference, we manipulated the relatedness of the tasks. In Experiment 1, subjects searched concurrently for names of boys in one channel and names of cities in another channel. Responses were significantly delayed when a nontarget on one channel belonged to, or was even just related to, the category designated as the target for the other channel. No comparable effects were found when the tasks were performed in isolation. Thus, the difficulty of the individual tasks is not the only determinant of how much they will interfere when combined, and there must be substantial interactions between processes carrying out the two tasks. In Experiment 2 subjects searched one channel for specific target letters and another channel for specific target digits. The nontargets in a channel were either from the same alphanumeric category as the targets for that channel or from the opposite category (i.e., the category of the targets for the other channel). It was found that although between-category search was more efficient than within-category search in single tasks, it was less efficient in dual tasks. Thus, there appear to be significant task interactions due to the confusability emerging when the nontargets of one task belong to the same category as the targets of the concurrent task. In addition, the congruence of target presence or absence on the two channels was found to have a sizeable effect. We suggest four potential sources of outcome conflict that may contribute to dual-task interference, and we conjecture that a great deal of the residual interference might result from other sorts of outcome conflict.     

Gender differences in spatial navigation: Characterizing wayfinding behaviors

Psychonomic Bulletin & Review - Men show a consistent spatial navigation advantage over women, which is often attributed to their increased use of survey spatial strategies. But what about...     

Sex differences for selective forms of spatial memory

In the present study, a systematic comparison of sex differences for several tests of spatial memory was conducted. Clear evidence for more accurate male performance was obtained for precise metric positional information in a wayfinding task and in an object location memory task. In contrast, no sex difference characterized topological information processing (object-to-position assignment). Together, these findings provide further insight in the specificity of sex differences in spatial memory and in the functional architecture of spatial memory. Implications for the relevant evolutionary basis are discussed.     

Sex differences in the personality and cognitive correlates of spatial ability

Ozer (1987) found that spatial visualization correlated with personality and verbal ability for girls but not for boys. To account for this finding, he hypothesized that "the causes of individual differences in spatial visualization [may be] different for the two sexes" (Ozer, 1987, p. 134). Although Ozer's conclusion is an intriguing one, it should be viewed with at least some skepticism until the discrepancies between his data and those of other researchers have been reconciled.     

Sex differences in spatial ability reflected in performance on IQ subtests by black or white examinees

Sex differences in spatial ability were investigated using scores on the performance subtests of the Wechsler Intelligence Scale for Children. The sample consisted of 832 adolescents, evenly divided by race (black or white) and sex. Within both racial groups, males outscored females on all of the spatially-oriented subtests, but females outscored males on a subtest emphasizing rote memory. The similarity of patterning of sex differences within each racial group might be interpreted as indicating that something more than social experience alone is involved in this phenomenon.     

A preliminary study of sex differences in brain activation during a spatial navigation task in healthy adults

The hippocampus plays a significant role in spatial memory processing, with sex differences being prominent on various spatial tasks. This study examined sex differences in healthy adults, using functional magnetic resonance imaging (fMRI) in areas implicated in spatial processing during navigation of a virtual analogue of the Morris water-maze. There were three conditions: learning, hidden, and visible control. There were no significant differences in performance measures. However, sex differences were found in regional brain activation during learning in the right hippocampus, right parahippocampal gyrus, and the cingulate cortex. During the hidden condition, the hippocampus, parahippocampal gyrus, and cingulate cortex were activated in both men and women. Additional brain areas involved in spatial processing may be recruited in women when learning information about the environment, by utilizing external cues (landmarks) more than do men, contributing to the observed sex differences in brain activation.     

The attenuation effect in timing: counteracting dual-task interference with time-judgment skill training

A basic finding in the time-perception literature is an interference effect in dual-task conditions involving concurrent timing and distractor tasks. Dual-task conditions typically cause time judgments to become less accurate than single-task conditions in which subjects judge time alone. Previous research (Brown, 1998 Psychological Research 61 71-81; Brown and Bennett, 2002 Psychological Research 66 80-89) has shown that practice on the distractor task reduces interference, a phenomenon called the attenuation effect. The present research was designed to determine whether practice on the time-judgment task would produce a similar result. In experiment 1, subjects reproduced 6-14 s intervals in a series of practice trials. Some subjects received feedback regarding the accuracy of each response and others received no feedback. Subsequent testing under dual-task (timing + digit memory) conditions showed that feedback training reduced interference. In experiment 2, the practice trials included both single-task and dual-task conditions. Later tests showed that feedback training eliminated the interference effect. The results highlight the role of attentional resources, the transfer of skills, and compensatory decision processes in time-judgment skill training.     

Single landmark learning in rats: Sex differences in a navigation task

In Experiments 1 and 2, rats were trained in a Morris pool to find a hidden platform located some distance away from a single landmark. Males learned to swim to the platform faster than females, but on test trials without the platform, males, unlike females, spent less time in the platform quadrant of the pool in the second half of each test trial than in the first. They also showed greater persistence in searching in the platform quadrant over a series of extinction trials. In Experiments 3a and 3b, the problem was made easier by locating the platform closer to the solitary landmark. Now males and females learned to swim to the platform equally rapidly, and both stopped searching in the platform quadrant in the second half of each test trial. Experiment 4 ruled out the possibility that males´ shorter latencies to find the platform in Experiment 2 were due to their swimming faster than females.     

Sex differences in the alcohol deprivation effect in rats

Few studies have investigated the relationship between early onset of alcohol drinking and relapse in adulthood, which may be larger in females, as revealed by studies using rats as subjects. The present study assesses the alcohol deprivation effect (ADE) in adult rats of both sexes that began alcohol consumption during preadolescence or adolescence. Female and male Wistar rats received free-choice access to water, 5, 10 and 20% (v/v) ethanol solutions during the ethanol exposures. The effects of age and sex on ADE in adult rats were assessed after repeated periods of abstinence. The results showed that female but not male rats increased ethanol intake after the second and third deprivation (showing ADE), irrespective of the onset-age of alcohol drinking.     

Additional effects of a cognitive task on dual-task training to reduce dual-task interference

ObjectiveWhen we perform dual-tasks in daily life, task performance is generally reduced. As these reductions in performance (i.e., dual-task interference) are responsible for various accidents such as falls, the repeated practice of dual-task (i.e., dual-task training) is often implemented to reduce dual-task interference. However, the risk of various accidents increases with longer dual-task training, as dual-task interference cannot be avoided. Therefore, it is important to achieve training goals more rapidly during dual-task training. This study sought to determine whether a combination of dual-task training and cognitive tasks would accelerate training effects.DesignThe experimental design included four groups: 1) cognitive task training group, 2) dual-task training group, 3) cognitive task and dual-task training group, and 4) non training group.MethodWe assessed single- and dual-task performance before and after the 2-week training sessions. We adopted a dual-task involving knee extension and an auditory reaction, and used N-back task as a cognitive task. On the other hand, dual-task training was the same method to assess dual-task performance.ResultDual-task interference was reduced in all groups in both the tasks. However, the number of participants in the cognitive task and dual-task training group who achieved a reduction in dual-task cost was significantly higher than those in other groups.ConclusionThese findings could contribute to the development of an effective method for reducing dual-task interference and resolving issues caused by dual-task interference in daily life.     

Electrodermal responses to sources of dual-task interference

There is a response selection bottleneck that is responsible for dual-task interference. How the response selection bottleneck operates was addressed in three dual-task experiments. The overlap between two tasks (as indexed by the stimulus onset asynchrony [SOA]) was systematically manipulated, and both reaction time and electrodermal activity were measured. In addition, each experiment also manipulated some aspect of the difficulty of either task. Both increasing task overlap by reducing SOA and increasing the difficulty of either task lengthened reaction times. Electrodermal response was strongly affected by task difficulty but was only weakly affected by SOA, and in a different manner from reaction time. A fourth experiment found that the subjectively perceived difficulty of a dual-task trial was affected both by task difficulty and by SOA, but in different ways than electrodermal activity. Overall, the results were not consistent with a response selection bottleneck that involves processes of voluntary, executive attention. Instead, the results converge with findings from neural network modeling to suggest that the delay of one task while another is being processed reflects the operation of a routing mechanism that can process only one stream of information for action at a time and of a passive, structural store that temporarily holds information for the delayed task. The results suggest that conventional blocked or event-related neuroimaging designs may be inadequate to identify the mechanism of operation of the response selection bottleneck.