Association between processes of hemispheric selection of information in the modified Stroop task and creative achievements

Relationships between creative abilities and indices of selective attention were studied in lateralized serial Stroop Test presented in two conditions: color and word integrated or separated in a stimulus. The study enrolled 69 male and female subjects who were divided into high- and low-creative achievement groups by mean split of the originality score in figural tasks of Torrance Tests of Creative Thinking. It was found that features of hemispheric organization of selective attention assessed by the difference in reaction time to incongruent and a congruent color-word stimuli pairs individually administered in the right and left visual hemifields were differently correlated with creative abilities of men and women. High creativity of men was associated with lower attention-related selective processes in the right hemisphere and inversion of hemispheric asymmetry (as compared to low-creative men). There was no difference in these parameters between high- and low-creative women. Independently of gender, hemispheric asymmetry of selective attention indices reversed after transition from integrated to spatially separated presentation of color and word, which provided evidence for the use of flexible strategies.     

Hemispheric interactions during a search of original verbal associations: EEG coherence in creative men and women

A hemispheric interaction during verbal creative thinking was studied by the analysis of EEG coherence in the band of 4-30 Hz. 18 males and 21 females (right-handed university students) participaited in the experiments. Independently of gender, the performance of Remote Associates Task was accompanied by an increase in coherence in the theta1 and beta2 frequency bands as compared to the states of rest and the letter-fluency and simple associate's tasks. Successful search for original word associates as compared to generation of standard words was accompanied by a local increase in the interhemispheric coherence of the beta2 rhythm mostly in the parietotemporal cortex. In creative men, the increase in the hemispheric interaction efficient for a search for original words was focused in the frontal and temporal loci of the right hemisphere and in the left occipital locus, whereas in creative women the increase in coherence was observed in the left frontal and temporal regions. Creative men differed from non-creative ones by higher inter- and intrahemispheric coherence and were similar to women in the level of hemispheric interaction. The cortical distribution of foci of interhemispheric coherence reactivity indicates that the cortical organization of verbal functions depends on both sex and creativity of men and women.     

Frequency-spatial organization of brain electrical activity in creative verbal thinking: role of the gender factor

Gender differences in EEG patterns associated with verbal creativity were studied by EEG mapping. The EEGs of 18 males and 21 females (right-handed university students) were recorded during a performance of Remote Associates Task (RAT) compared with the letter-fluency and simple associate's tasks. Gender differences were found in a factor structure of the indices of verbal thinking and a score of generating words was greater in women than men. No significant gender differences in originality of associations were revealed, however, gender-related differences in the EEG-patterns were found at the final and initial stages of RAT. In men, the beta2-power was increased in both hemispheres at the beginning of test. To the end of testing, the power of oscillations in the beta2 band increased only in the central part of the cortex. In women, the beta2-power was increased to a greater extent in the right than in the left hemisphere at the initial stage of task performance, whereas the final stage was characterized by a relative decrease in beta-activity in parietotemporal cortical regions and increase in the left prefrontal region. It is suggested that the verbal creative thinking in men is based mostly on "insight" strategy whereas women additionally involve the "intellectual" strategy.     

Changes in the EEG power in male and female subjects during visual creative thinking

Gender-related differences in EEG patterns during creative visual thinking were investigated in 10 men and 10 women. The spectral power density was analyzed in the range of 4-30 Hz. Gender differences in the hemispheric asymmetry of theta1-rhythm desynchronization were found: females demonstrated greater desynchronization in the right hemisphere than in the left hemisphere, whereas no asymmetry was revealed in males. Only in women numerous negative correlations between creativity indices and task-induced theta1 desynchronization were found.     

Relationship between creativity and hemispheric information processing: effect of handedness

Effect of handedness in creativity-related global and local hemispheric selective processing was examined with lateralized presentation of hierarchical letters. Eighty-four university students (aged 17-22 years) participated in the study. Handedness was determined by Annett questionnaire. Originality of imagery was assessed by a computer-based Torrance 'Incomplete Figures' test. Verbal creativity was assessed by the results of the sentence construction with three nouns belonging to remote semantic categories. The results show that higher figural originality is provided by an increase in both right-hemispheric and interhemispheric interference processes at the global/local or congruent/noncongruent level. Verbal originality is associated with an increase in the right-hemispheric interference between congruent and noncongruent stimuli at the local attention level and with a decrease in interhemispheric interference at the global level. A decrease in the typical preference of the right hand is accompanied by the higher creativity and acceleration of the right-hemispheric interference processes.     

The influence of reward on the performance of verbal creative tasks: Behavioral and EEG effects

The goal of this study was to compare the effects of the verbal instruction (IN1) that stimulated originality and of monetary reward (IN2) on the efficiency of performing a verbal creative task. The EEG patterns were also compared on the basis of mapping the bioelectric potential power within the frequency range of 4 to 30 Hz. Right-handed students (10 men and 10 women) participated in the experiment. The originality of the solution improves if a monetary reward is expected. In contrast to IN1, the promise of a monetary reward caused a global increase in task-related synchronization of bioelectric potentials in the θ₂ band. Hemispheric asymmetry of the power of the θ₁, θ₂, and α₂ rhythm grows with higher values in the right hemisphere. These changes in response to IN2 were in the background EEG, which testifies that an overall increase in hemispheric asymmetry induces a preparatory state after the promise of monetary reward. Specific changes in regional brain activity were at the β₂-rhythm frequency. In all posterior derivation, except for the frontotemporal ones, the power of the β2 rhythm decreased in response to IN2 in contrast to IN1. The rewardinduced changes in EEG were characteristic of men to a greater extent. An increase in the θ₂-rhythm asymmetry and the power of the α rhythm was observed only in men in response to a monetary reward. Our results suggest that the promise of monetary reward is favorable for creative thinking and original solutions. Gender differences of changes in the power of bioelectric potentials suggest that the neurophysiological mechanisms of creativity are different in men and women.     

The study of interhemispheric asymmetry in spatial-perceptive problem solving

Features of brain interhemispheric asymmetry during solving the spatial figurative task (maze model) were studied in men and women with different intelligence quotients (IQ). It was shown that during task solving the rate of information processing was higher in the right brain hemisphere, and amplitude characteristics of the event-related potentials were higher in the left hemisphere. No gender and IQ differences in the character of interhemispheric interaction were found during the realization of the maze-model task. The results testify that the character of hemispheric interaction depends om the task rype rather than gender and intelligence level.     

Information processing specialization during interference between global and local aspects of visual hierarchical stimuli in men and women

Sex-related differences in global/local hemispheric selective processing were examined by hierarchically presented letters in conditions of their perception and comparison. Fifty-six right-handed men and 68 women (aged 17–22 years) participated in the experiment. During the interference between global and local aspects of stimuli, the mean reaction time for correct global responses was shorter than for local responses, and the right hemisphere dominated during global selective processing independently of sex. Sex-related differences in perception of visual hierarchical stimuli were more pronounced than during their comparison: men preferred the right-hemispheric global strategy of information processing, and women, the left-hemispheric local one. The dominance of the global strategy in men and local strategy in women during visual hierarchical stimuli perception, together with the absence of sex-related differences in correct responses indicates the possibility of obtaining the same efficiency of cognitive activity in different ways.     

Selection of visual hierarchical stimuli between global and local aspects in men and women

Sex differences in global-local hemispheric selective processing were examined by hierarchical letter presenting in conditions of their perception and comparison. Fifty-six right-handed males and 68 females (aged 17-22 years) participated in the experiment. During interference between global and local aspects of stimuli the mean reaction times for correct global responses was quicker than local responses, and the right hemisphere has been dominated during global selective processing independently from the sex. Sex differences in perception of visual hierarchical stimuli were more pronounced than in comparison condition: men prefer mostly the right-hemispheric global strategy of information processing, but women--the left-hemispheric local one. Dominance of global strategy in men and local strategy in women during visual hierarchical stimuli perception together with no sex differences in correct responses indicates possibility of similar results in cognitive activity by different ways.     

Strategy and results: Sex differences in electrographic correlates of verbal and figural creativity

Sex differences in electroencephalographic (EEG) correlates of creativity were studied using verbal and figural divergent tasks to be performed in accordance with the instructions to “give any solution” or “give an original solution.” The common effect was a greater activity of the right hemisphere, which did not depend on the sex, task type, or instructions for performance of the tasks. The α₂ and β₂ rhythms were the main EEG frequency correlates of creative thinking; the degree and sign of their reactivity depended on the aforementioned factors. Although the creative abilities in men and women were similar under test conditions, the EEG correlates of both figural and verbal tasks were sex-dependent. A high reactivity of the α₂ rhythm was more marked during verbal creative thinking in women; and that of the β₂ rhythm, during figural creative thinking in men. The instruction-related improvement of the critical selection of solutions was to a greater extent reflected by changes in the cortical activity, more pronounced in the frontal cortex in the women. Thus, the same creative productivity in men and women was mediated by different strategies of performance of both figural and verbal tasks, and the sex-related differences in these strategies remained even when the motivation for creativity was changed.     

Motivation effect on power changes in the brain biopotentials in the figurative and verbal creativity tasks

Effect of extrinsic motivation stimulating the most original problem solving during verbal and figurative divergent thinking was studied by EEG mapping. The righthanded university students (27 males and 26 females) participated in the experiments. An instruction "to create the most original solution" as compared to condition with an instruction "to create any solution" induced an increase in the baseline power of the alpha 1 and alpha 2 rhythms most pronounced in the posterior cortex. Task-related desynchronization of the alpha rhythms was higher but the beta-2 synchronization was lower after the former than after the latter instruction. Differences in the asymmetry of the alpha 1 and alpha 2 rhythms in the parietal and temporal regions of hemispheres suggested the right hemisphere dominance in intrinsic alertness and evoked activation related to divergent thinking. The findings were common and gender-independent in both figurative and verbal tasks suggesting a generalized influence of extrinsic motivation on creative activity.     

Switching between forest and trees: Opposite relationship of progesterone and testosterone to global–local processing

Sex differences in attentional selection of global and local components of stimuli have been hypothesized to underlie sex differences in cognitive strategy choice. A Navon figure paradigm was employed in 32 men, 41 naturally cycling women (22 follicular, 19 luteal) and 19 users of oral contraceptives (OCs) containing first to third generation progestins in their active pill phase. Participants were first asked to detect targets at any level (divided attention) and then at either the global or the local level only (focused attention). In the focused attention condition, luteal women showed reduced global advantage (i.e. faster responses to global vs. local targets) compared to men, follicular women and OC users. Accordingly, global advantage during the focused attention condition related significantly positively to testosterone levels and significantly negatively to progesterone, but not estradiol levels in a multiple regression model including all naturally cycling women and men. Interference (i.e. delayed rejection of stimuli displaying targets at the non-attended level) was significantly enhanced in OC users as compared to naturally cycling women and related positively to testosterone levels in all naturally cycling women and men. Remarkably, when analyzed separately for each group, the relationship of testosterone to global advantage and interference was reversed in women during their luteal phase as opposed to men and women during their follicular phase. As global processing is lateralized to the right and local processing to the left hemisphere, we speculate that these effects stem from a testosterone-mediated enhancement of right-hemisphere functioning as well as progesterone-mediated inter-hemispheric decoupling.     

The hemispheric lateralization of the recognition of noisy visual stimuli in man

At tachistoscopic unilateral presentation of noisy visual stimuli and application of "yes-no" method in man predominance was found of the right hemisphere by the number and "yes" reaction time and of the left hemisphere by the number of responses "no". At verbal mnemic load preceding the presentation of visual patterns the left hemisphere asymmetry was observed by the number of "yes" responses and reactions time of both types. FMA was more clearly expressed in men in the first case and in women--in the second one. In more difficult conditions of recognition of several types of patterns, FMA was noticed mainly in women: initial left hemisphere advantage during the increase of the disturbance was changed to the right hemispheric one and appeared again. Preferential participation of the right hemisphere in singling out of the visual signal from noise is supposed. Possibility of the left hemispheric asymmetry manifestation was determined by the specificity and complexity of the visual task, by the level of the disturbance, presentation of competitive task and sexual composition of the group.     

Sex differences in EEG power changes in retention of dichotically and monaurally presented verbal stimuli

EEG power mapping was used to study gender differences in hemispheric functional organization during memorizing dichotically and monaurally presented verbal information. Right-handed students (12 men and 14 women) participated in experiments. The EEG was recorded from 16 electrodes placed at homologous sites of the left and right brain hemispheres. Task-related changes in the thetal power in men differentiated between monaural presentations to different ears, i.e., situations of oppositely directed attention. In women the thetal power reactivity (the difference between the band power logarithms under baseline conditions and in task interval) differentiated between dichotic and monaural presentations of words, i.e., situations with different memory loads. Gender differences were also found in the alpha frequency band. Power changes in the alpha 1 band in all memory tasks and power changes in the alpha 2 were more evident in the right hemisphere in men but in the left hemisphere in women. In contrast, in the posterior temporal lead the alpha 2 power reactivity in men was higher in the right hemisphere, whereas in women the lateral differences were absent. As compared to men, the alpha 2 desynchronization in women was also more pronounced in posterior regions of both hemispheres. There were no gender differences in efficacy of memorizing. It is suggested that different processing strategies rather than different behavioral performance may be responsible for the revealed specific spatiotemporal EEG patterns.     

Gender-Dependent Frequency-Spatial Organization of the Brain Cortex Activity during Convergent and Divergent Thinking: II. Analysis of the EEG Coherence

The gender dependence of inter- and intrahemispheric interactions of neuronal assemblies during convergent (CTh) and divergent (DTh) thinking was studied on the basis of analysis of coherence (Coh) of cortical potentials in a broad frequency band. CTh was studied with a model of mental arithmetic, and DTh, with a heuristic task. Right-handed subjects were examined. The distinctive feature of CTh was a functional change in the patterns of EEG Coh in the θ band. Men were characterized by an increase in interactions between the centro-parieto-occipital areas of both hemispheres and between the frontal and temporooccipital regions of the right hemisphere, whereas a similar pattern of coherent connections was shifted to the left temporal area in women, suggesting a predominant use of verbal calculation strategies by women and visuospatial strategies by men. Regardless of the gender, DTh was associated with an increase in interhemispheric Coh and an increase in Coh in the right hemisphere. However, the successful performance of a task in men and women was determined by different degrees of hemispheric interaction: men successfully solved the problem under conditions of a closer interaction of both hemispheres, whereas women efficient in their performance showed a weaker interaction of homologous cortical areas as compared to noncreative subjects.__________Translated from Fiziologiya Cheloveka, Vol. 31, No. 3, 2005, pp. 39–49.Original Russian Text Copyright © 2005 by Razoumnikova.     

Cardiorespiratory response to hypoxia in persons with different levels of creativity

The correlation between the parameters of creativity and tolerance to experimentally induced normobaric hypoxia has been studied in young healthy subjects. The subjects inhaled a low-oxygen gas mixture (10% O₂) until the arterial hemoglobin oxygen saturation (SaO₂) decreased to 80%. In the recovery period, the subjects breathed normoxic air until the SaO₂ returned to its initial value. The parameters of creativity, including the originality and fluency of producing images in Torrance’s subtests of Circles and Incomplete figures, as well as the originality and fluency of sentences composed by using nouns from distant semantic categories, were evaluated before conducting hypoxic tests. Positive relationships were found between the values of figurative originality and tolerance to hypoxia, i.e., by the time of decrease in SaO₂ and the coefficient that reflects the rate of recovery of the respiratory function. Analysis of the reactivity of the cardiovascular system showed negative correlations between the parameters of creativity, namely, the figurative originality and verbal fluency, and the heart rate under the conditions of hypoxia, as well as after the recovery of the functions of the cardiorespiratory system. An increase in the capacity for original figurative thinking also corresponded to smaller differences in the values of the heart rate during the recovery and at rest. These correlations between the characteristics of creative thinking and reactions of the cardiovascular and pulmonary systems to experimentally induced hypoxia indicate that there is a common mechanism of nervous regulation underlying adaptive behavior and maintaining homeostasis.     

Sex Differences and Activity of the Left and Right Brain Hemispheres

The problem is reviewed of sex differences and the brain organization of the visual-spatial and verbal-cognitive functions both in adults and in the 5–15-year old children. Characteristic of men are the integral strategy of the face image recognition, specialization of the right hemisphere for visual-spatial functions, and the tonic inhibitory effect of the right hemisphere on the left one. Typical of women are the fragmented type of the image recognition, the equality of the brain hemispheres functions at the unfamiliar face recognition, and predominance of the left hemisphere by accuracy of the object localization in the visual field. It is possible that the general strategy of the recognition in women is not realized due to the right hemisphere submitted to the interfering effect of the left hemisphere. Analysis of sex differences in distribution of verbal functions shows that the capability for the verbal learning at the age of 5 years and older is higher in girls than in boys. Such capability seems to be accounted for by the superiority of the left hemisphere in girls in this type of its activity and by its earlier development and maturation. The phenomenon of semantic paralexia appearing more often in boys is accounted for by inclusion of lexical-semantic fields of the right hemisphere symmetric areas in the verbal-cognitive activity There are reasons to believe that the higher capability in girls for the verbal learning is mainly due to processes of the auditory-verbal integration within the limits of the left hemisphere, whereas this verbal ability in boys depends on the relative predominance of the interhemispheric connections.     

Gender differences in hemispheric interaction during distributed and directed attention

Gender differences in the functional hemispheric organization during memorization of dichotically presented verbal information in the situation of focused or non-focused attention were studied. Analysis of EEG coherence reactivity in six frequency bands (4-30 Hz) showed that the focused attention to stimuli presented to one ear as compared to divided attention between both ears was accompanied by an increase in the interhemispheric interaction in the thetal frequency band between the frontal cortical areas in men and between the parietoccipital areas in women. In the betal band, the focused attention was associated with a contralateral increase in the intrahemispheric coherence in men, whereas no significant difference in the intrahemispheric coherence was found in women. On the basis of coherence changes in the thetal and betal bands depending on the attention conditions together with the obtained correlation between coherence reactivity and word-recall scores, it may be suggested that verbal memorization in men is associated, predominantly, with the regulation from the anterior system of attention and from the posterior system in women.     

The impact of experimental instruction on changes in EEG power during verbal creative thinking in men and women

Features of EEG pattern during verbal creative thinking depending on experimental instruction were studied in men and women. Spectral power density was analyzed in six frequency bands (4-30 Hz). Performance of a creative task produced an increase in the power of theta (4-6 Hz) and beta2 (20-40 Hz) components and decrease in the power of alpha (8-13 Hz) and betal (13-20 Hz). Changes in the alpha and betal bands were observed, predominantly, in the posterior areas, whereas power of the thetal and beta2 bands increased in the anterior areas. Independently of instruction, women demonstrated greater synchronization in the theta1 band than men, whereas in men the desynchronization in the alpha2 band (10-13 Hz) was more pronounced. When the subjects were instructed to create original sentences, a widespread decrease in the EEG power was observed in the band of 8-30 Hz as compared to instruction "to create sentences". Thus, the instruction-related changes in EEG power were not gender-specific. They may reflect neural activity mediating selective attention.     

EEG study of the functional organization of the right and left hemisphere during solution of verbal and spatial problems

In adult healthy right-handed subjects, the expression and degree of synchronization of the EEG alpha-range rhythmic components in different areas of the right and left hemispheres, were studied in a state of quiet wakefulness and during solving of verbal and spatial tasks presented in the visual field. The EEG of quiet wakefulness was characterized by different distribution of the alpha-range rhythmic components in the right and left hemispheres; in the right hemisphere low frequencies (7.5-10.5 c/s) were more expressed and more coherent; in the left one--the high frequencies (10.5-13.5 c/s). The solving of tasks was accompanied--along with a decrease of the whole alpha-range power spectra both in the right and the left hemispheres--by a local increase of synchronization of certain components of this range; the increase was specific to the hemisphere and the kind of task. The increase of synchronization of low-frequency components was observed in the right hemisphere during solving of the spatial task and that of the high-frequency components was noticed in the left hemisphere during solving of the verbal task. On the basis of the data on hemispheric specificity of electric activity synchronization of the alpha-rhythm, a suggestion is made about a different character of the functional integration of the structures of the right and left hemispheres in the process of solving of spatial and verbal tasks.