Sex Differences in Number Magnitude Processing Strategies Are Mediated by Spatial Navigation Strategies: Evidence From the Unit-Decade Compatibility Effect

The hybrid model of number magnitude processing suggests that multi-digit numbers are simultaneously processed holistically (whole number magnitudes) and in a decomposed manner (digit magnitudes). Thus, individual tendencies and situational factors may affect which type of processing becomes dominant in a certain individual in a given situation. The unit-decade compatibility effect has been described as indicative of stronger decomposed number processing. This effect occurs during the comparison of two-digit numbers. Compatible items in which the larger number contains the larger unit digit are easier to solve than incompatible items in which the larger number contains the smaller unit digit. We have previously described women show a larger compatibility effect than men. Furthermore, the compatibility effect is modulated by situational factors like the vertical spacing of the presented numbers. However, it has not been addressed whether situational factors and sex affect the unit-decade compatibility effect interactively. We have also demonstrated that the unit-decade compatibility effects relates to global-local processing, which in turn also affects spatial processing strategies. However, a link between spatial processing strategies and the unit-decade compatibility effect has not yet been established. In the present study we investigate, whether sex differences in the unit-decade compatibility effect (i) depend on the vertical spacing between numbers, (ii) are mediated via sex hormone levels of participants, and (iii) relate to sex differences in spatial processing strategies. 42 men and 41 women completed a two-digit number comparison task as well as a spatial navigation task. The number comparison task modulates compatibility and vertical spacing in a 2 × 2 design. The results confirm a larger compatibility effect in women compared to men and with dense compared to sparse spacing. However, no interactive effect was observed, suggesting that these factors modulate number magnitude processing independently. The progesterone/testosterone ratio was related to the compatibility effect, but did not mediate the sex difference in the compatibility effect. Furthermore, spatial processing strategies were related to the compatibility effect and did mediate the sex difference in the compatibility effect. Participants with a stronger focus on landmarks in the spatial navigation task showed a larger compatibility effect

Brain Connectivity / Sex hormones modulate the relationship between global advantage, lateralization, and interhemispheric connectivity in a navon paradigm

Sex, stimulus material, and attention condition have previously been related to global advantage (GA; faster responses to global targets than to local targets) on the one hand and lateralization during globallocal processing on the other hand. It is presumed that the lateralization of brain functions is either related to the inhibitory influence of the dominant on the nondominant hemisphere or reduced excitation between hemispheres. However, a direct relationship between the GA and lateralization and interhemispheric connectivity has not been previously established. In this study, 58 participants (29 men, 29 naturally cycling women) completed a Navon paradigm, modulating attention condition (divided vs. focused) and stimulus material (letters vs. shapes) during functional magnetic resonance imaging. The size of the GA effect, lateralization indices, interhemispheric connectivity, and sex hormone levels were assessed. In summary, this study suggests that interhemispheric connectivity during globallocal processing is affected by sex and material. Furthermore, the relationship between interhemispheric connectivity, lateralization, and behavior was modulated by sex and sex hormones. Results suggest (1) differential roles of interhemispheric connectivity for lateralization in men and women and (2) differential roles of lateralization for behavior in men and women. Importantly, the classic assumption that a more negative connectivity leads to stronger lateralization, which in turn leads to a stronger GA effect, was observed in men, whereas the opposite pattern was found in women. The relationship between connectivity and lateralization was mediated through testosterone levels, whereas the relationship between lateralization and behavior was mediated through progesterone levels. Results are discussed in light of differential functions of inhibitory and excitatory interhemispheric processes in men and women.P28261(VLID)253310

Evaluating achievement on mathematics and science problems: The role of global and local processing

This thesis sought to clarify relationships between whole-part constructs; where responses are thought to reflect a focus on the whole stimulus or context, or on individual elements (the parts). Children aged 5 to 10 years completed a number of tasks allowing developmental changes to be measured on a cross-sectional and longitudinal basis. Global and local processing tasks (Navon tasks: free choice, selective attention, and divided attention) revealed a change in response patterns between the ages of 6 and 7 years, the precise nature of which varied depending on the attentional demands of the task. Field independence tasks (Children’s Embedded Figures Test (CEFT) and Design Organisation Test (DOT)) revealed that children became more field independent with increasing age. A parental questionnaire measuring systemizing (the analysis or construction of a rule-based system) was administered at a single timepoint and revealed no cross-sectional age-related changes. Behavioural tasks and eye-tracking technology were employed to understand possible mechanisms underlying field independence performance. Visuospatial IQ and working memory explained variation on both field independence tasks. Higher accuracy on the CEFT reflected fewer and shorter fixations on distractor areas as well as longer and more fixations on target areas. Better response inhibitory control related to higher disembedding accuracy, while better semantic inhibitory control related to fewer and shorter fixations on distractor areas. Together, these explain how domain-general factors contribute to performance on the CEFT. The second part of this thesis examined associations between whole-part constructs and mathematics and science achievement. Global and local processing and systemizing revealed few significant associations with the academic scores. Better field independence was associated with higher scores on both mathematics and science. After controlling for age and domain-general factors, the field independence tasks explained additional variance on specific mathematics and science tests, which likely reflect common processes involved in the tasks