An fMRI study of sex differences in regional activation to a verbal and a spatial task

Sex differences in cognitive performance have been documented, women performing better on some phonological tasks and men on spatial tasks. An earlier fMRI study suggested sex differences in distributed brain activation during phonological processing, with bilateral activation seen in women while men showed primarily left-lateralized activation. This blood oxygen level-dependent fMRI study examined sex differences (14 men, 13 women) in activation for a spatial task (judgment of line orientation) compared to a verbal-reasoning task (analogies) that does not typically show sex differences. Task difficulty was manipulated. Hypothesized ROI-based analysis documented the expected left-lateralized changes for the verbal task in the inferior parietal and planum temporal regions in both men and women, but only men showed right-lateralized increase for the spatial task in these regions. Image-based analysis revealed a distributed network of cortical regions activated by the tasks, which consisted of the lateral frontal, medial frontal, mid-temporal, occipitoparietal, and occipital regions. The activation was more left lateralized for the verbal and more right for the spatial tasks, but men also showed some left activation for the spatial task, which was not seen in women. Increased task difficulty produced more distributed activation for the verbal and more circumscribed activation for the spatial task. The results suggest that failure to activate the appropriate hemisphere in regions directly involved in task performance may explain certain sex differences in performance. They also extend, for a spatial task, the principle that bilateral activation in a distributed cognitive system underlies sex differences in performance.     

Visual field differences in verbal tasks: Effects of task familiarity and sex of subject

Four experiments using normal subjects investigated differences in magnitude of the right visual field (RVF) superiority as a function of word material (frequency and concreteness/imageability status), nonword letter strings (some of which were homophonic with nonpresented real words), and type of task (overt naming or lexical decision with discriminatory manual responses) as well as sex of the subject and the subject's familiarity with the material. Both latency and error measures showed that RVF superiority was more consistent when overt naming was required and with male subjects. For female subjects engaged in lexical decisions, a left visual field (LVF) superiority was often apparent, especially in the first half of an experimental sequence; when actually naming the items aloud, they showed field asymmetries similar to males. Except from an analysis of errors, there was little evidence to support differential right hemisphere mediation of high frequency concrete/imageable materials. It is suggested that in females, right hemisphere space normally reserved for visuospatial processing may have been invaded by secondary speech mechanisms. These mechanisms appear to operate at an essentially lexical level and may act in a supportive or auxiliary capacity for difficult or unfamiliar material; they seem to be equally concerned with both phonological and graphological processing and may account for the well-known female superiority in verbal tasks and inferiority in visuospatial tasks. Other findings are discussed such as the degree of consistency of the field differences, both for the same subjects and for the same stimulus materials under different task requirements and experimental conditions.     

Sex differences in verbal fluency: a short note

Adult male and female subjects performed two fluency tasks from the ‘Kit of Reference Tests for Cognitive Factors’. Although both word fluency and ideational fluency are said to show female superiority, a significant difference in favour of females could be found only in the task which primarily requires lexical access and not in the task requiring mental access to colour and form of objects.     

Sex differences in verbal fluency: a short note

Adult male and female subjects performed two fluency tasks from the 'Kit of Reference Tests for Cognitive Factors'. Although both word fluency and ideational fluency are said to show female superiority, a significant difference in favour of females could be found only in the task which primarily requires lexical access and not in the task requiring mental access to colour and form of objects.     

Adult age differences in interference from a prospective-memory task: a diffusion model analysis

People often slow down their ongoing activities when they must remember an intended action, known as the cost or interference effect of prospective memory (PM). Only a few studies have examined adult age differences in PM interference, and the specific reasons underlying such differences are not well understood. The authors used a model-based approach to reveal processes underlying PM interference and age differences in these processes. Older and younger adults first performed a block of an ongoing lexical decision task alone. An embedded event-based PM task was added in a second block. Simultaneously accounting for the changes in response time distributions and error rates induced by the PM task, Ratcliff’s (Psychological Review 85:59–108, 1978) diffusion model was used to decompose the nonlinear combination of speed and accuracy into psychologically meaningful components. Remembering an intention not only reduced processing efficiency in both age groups, but also prolonged peripheral nondecision times and induced response cautiousness. Overall, the findings suggest that there are multiple, but qualitatively similar factors underlying PM task interference in both age groups.     

Individual differences in the use of simplification strategies in a complex decision-making task

Decision time results were used to assess the strategies that 90 college undergraduates used in a complex decision-making task. Trend analyses revealed that the functions relating choice time to the number of choice alternatives in a set and the number of attributes comprising those alternatives contained linear (increasing) components. In addition, for a portion of the subjects, there was a quadratic effect of the number of attributes available to the decision maker on choice time, suggesting that these subjects adopted simplification strategies at high levels of task complexity. Reliable individual differences in these trend components were observed, consistent with individual differences in motivation and/or processing capacities. These individual differences were included in an information-processing model of decision behavior that captured the choice time data observed in this study. Subjects' ratings of apartments were used as a basis to assess the extent to which the use of simplification strategies resulted in preference reversals. Contrary to expectation, subjects whose choice times contained quadratic components demonstrated fewer preference reversals at high levels of information load.     

Hypnotic susceptibility and verbal automaticity: automatic and strategic processing differences in the Stroop color-naming task.

The original hypothesis of Dixon, Brunet, and Laurence (1990) that highly hypnotizable (HH) subjects process words more automatically than do low hypnotizable (LH) subjects was retested in a paradigm that separated strategic from automatic processes in the Stroop color-naming task. The words red and blue preceded a color patch that was red or blue. Subjects were told that the word predicted the opposite color 75% of the time. Automatic and strategic processes were assessed by varying the interstimulus interval (ISI) between the word and the color patch. Both HH and LH subjects showed significant strategic effects (faster incongruent-trial, color-naming reaction times than congruent-trial reaction times at ISIs over 400 ms), but only HH subjects showed significant automaticity (significantly faster congruent-trial reaction times than incongruent-trial reaction times at 16.7 ms, the lowest ISI).     

Visuo-spatial and verbal working memory in the five-disc Tower of London task: An individual differences approach

This paper reports a study of the roles of visuo-spatial and verbal working memory capacities in solving a planning task—the five-disc Tower of London (TOL) task. An individual differences approach was taken. Sixty adult participants were tested on 20 TOL tasks of varying difficulty. Total moves over the 20 TOL tasks was taken as a measure of performance. Participants were also assessed on measures of fluid intelligence (Raven's matrices), verbal short-term storage (Digit span), verbal working memory span (Silly Sentence span), visuo-spatial short-term storage (Visual Pattern span and Corsi Block span), visuo-spatial working memory (Corsi Distance Estimation), visuo-spatial processing speed (Manikin test), and verbal speed (Rehearsal speed). Exploratory factor analysis using an oblique rotation method revealed three factors which were interpreted as (1) a visuo-spatial working memory factor, (2) an age-speed factor, and (3) a verbal working memory factor. The visuo-spatial and verbal factors were only moderately correlated. Performance on the TOL task loaded on the visuo-spatial factor but did not load on the other factors. It is concluded that the predominant goal-selection strategy adopted in solving the TOL relies on visuo-spatial working memory capacity and particularly involves the active “inner scribe” spatial rehearsal mechanism. These correlational analyses confirm and extend results previously obtained by use of dual task methods, (Phillips, Wynn, Gilhooly, Della Sala, & Logie, 1999).     

A comparison of concurrent and retrospective verbal protocol analysis

In verbal protocol analysis, verbalization can occur either during decision making (concurrent data) or after (retrospective data). Although both methods have advantages and disadvantages, no empirical research has focused on a direct comparison. This study compared the effectiveness of concurrent and retrospective data for revealing the human decision making process. In general, the concurrent protocol analysis method outperformed the retrospective method. Not only was the number of concurrent protocol segments elicited higher than that of retrospective protocol segments, but concurrent data provided more insights into the decision-making steps occurring between stimulus introduction and the final choice outcome. However, retrospective protocols offer an interesting advantage: More statements about the final choice are provided in retrospective protocols than in concurrent protocols.     

Pictorial and verbal encoding in a short-term memory task

The present research attempted to manipulate the encoding modality, pictorial or verbal, of schematic faces with well-learned names by manipulating S’s expectations of the way the material was to be used. On every trial, a single name or face was presented, followed by another one; the S was asked to respond “same” if the stimuli had the same name, and “different” otherwise. The majority of second stimuli of any session was either names or faces. It was hypothesized that if S had encoded the first stimulus in the modality of the second, his judgment would be faster than if he had not appropriately encoded the first stimulus. Significantly slower reaction times were obtained to stimulus pairs where the second stimulus modality was infrequent. Further evidence that encoding of the first stimulus was in the frequent second stimulus modality comes from the finding that “different” responses were shorter when the stimuli differed on more than one attribute in the encoding (second stimulus) modality, regardless of the modality of the stimuli. Thus, evidence is presented that not only can verbal material be pictorially encoded (and vice versa), but that whether either verbal or pictorial material is verbally or pictorially encoded depends on S’s anticipation of what he is to do with the material.     

Image generation in a letter-classification task

Subjects classified briefly presented uppercase letters as belonging to the first or second half of the alphabet. A prior alternative preceded each target letter by 200 or 1,400 msec. It was either an ampersand (control), a lowercase letter (opposite case), or an uppercase letter (same case). In the latter two conditions, the target was equally likely to be identical in name to the prior alternative or from the opposite half of the alphabet. For the 200-msec onset asynchrony, classification accuracy was greater in the same-case condition than in the other two conditions, which did not differ. For the 1,400-msec onset asynchrony, accuracy in both the same- and opposite-case conditions was greater than accuracy in the control condition. Same- and opposite-case prior alternatives always biased subjects toward classifying the target in the same half of the alphabet as the alternative. The accuracy results suggest that internally generated images can be used to aid target classification in the opposite-case condition.     

Examining age differences in performance of a complex information search and retrieval task.

This study examined age differences in performance of a complex information search and retrieval task by using a simulated real-world task typical of those performed by customer service representatives. The study also investigated the influence of task experience and the relationships between cognitive abilities and task performance. One hundred seventeen participants from 3 age groups, younger (20-39 years). middle-aged (40-59 years), and older (60-75 years), performed the task for 3 days. Significant age differences were found for all measures of task performance with the exception of navigational efficiency and number of problems correctly navigated per attempt. There were also effects of task experience. The findings also indicated significant direct and indirect relations between component cognitive abilities and task performance.     

Visual vs. verbal stimulus set in a letter-classification task

In three experiments, subjects classified briefly presented letters as belonging to either the first or the second half of the alphabet. Prior to each target letter, the subjects were given either a verbally named letter (verbal set), a letter presented visually for 3 sec (visual set), or no prior alternative (control). The target was equally likely to be the same as the prior alternative (same trials) or from the opposite half of the alphabet (different trials). Classification accuracy was always greater for visual set than for the control condition. Verbal-set accuracy was no better than control accuracy when the verbal alternative immediately preceded the target but was equal to visual-set accuracy when the alternative preceded the target by 3 sec. In both set conditions, subjects tended to choose the same half of the alphabet as the prior alternative. It was concluded that type and timing of prior alternatives are important variables in accounting for enhanced classification accuracy.     

Part-set cuing in option generation

Memory research on the part-set cuing effect has shown that providing some of the to-be-remembered items as cues is not always beneficial and, in some cases, may even hurt retrieval. However, part-set cuing has been sparsely investigated in option generation tasks. Thus, limited empirical evidence for the existence of the effect in option generation is available, and no convincing explanation has been provided yet. In order to fill these gaps, we carried out four experiments. In Experiment 1A, we observed a significant decrease in option generation performance when potential options were presented as cues. Experiment 1B showed that the effect can also be obtained in older adults. Experiments 2A and 2B provided evidence compatible with an inhibition-based explanation of the observed effects.