Neural efficiency, intelligence and motivation

The tremendous cognitive variability found in human beings is the result of differences in brain functioning as well as in the exploitation of learning opportunities provided by the environment. The investigation of the neurophysiological correlates of psychometric intelligence has led to the development of the neural efficiency hypothesis (NEH), which postulates a more efficient use of brain resources in more intelligent people than in less intelligent ones. The NEH proves true for a wide spectrum of tasks ranging from quite simple ones to moderately difficult tasks, but may reverse for very high task difficulty. A possible explanation for the reversal of the neural efficiency phenomenon could be that in very difficult tasks brighter individuals devote more energy to the task, based on their conjecture that they can basically solve the task. In contrast, when less able individuals are working on a very complex task which seems to surpass their abilities, they take the deliberate decision to continue working without high commitment to the task. Consequently, it can be assumed that for difficult tasks motivation has a significant influence on the amount of invested cortical resources. An alternative explanation for the reversal of the neural efficiency phenomenon could be linked to the factor task order. It might be argued that for tasks with gradually increasing task difficulty less able participants might have already `run out of energy` when they come to work on very difficult tasks. This lack of energy might be due to the fact that less able participants have already consumed most of their (metabolic) energy when working on the easier and medium difficult tasks before. The proposed project aims at elucidating the NEH in detail and will therefore explore the moderating role of (1) task difficulty, (2) individual motivation and (3) task order with regard to task difficulty. For that purpose two fMRI studies shall be conducted. In the first study, we shall compare brain activation of 96 individuals with different intellectual ability and different trait achievement motivation. Participants will solve normatively easy vs. medium vs. difficult items (determined on the basis of classical item parameters, i.e., solution rates) that vary with regard to task order (ascending difficulty vs. random order). This first study shall shed light on the question whether individual achievement motivation and task order are a valid explanation for the reversal of the neural efficiency phenomenon with difficult tasks. In a second fMRI study, brain activation of 48 individuals with different intellectual ability and motivation is assessed while working on intelligence-related tasks, which differ in ipsative task difficulty (determined on the basis of person parameters obtained via item response theory). The second study shall elucidate the influence of ipsative task difficulty and trait motivation on the brain-activation*intelligence correlation. In sum, the suggested studies shall investigate the moderating influences of task difficulty, task order and trait motivation with respect to the neural efficiency phenomenon.

project Neural efficiency, intelligence and motivation (NEMO) was dedicated to the psychological and neuroscientific advancement in understanding human intelligence.Previous research showed that higher intelligent people display more efficient allocation of brain resources during cognitive processing than less intelligent ones. This neural efficiency phenomenon, however, seems to emerge only under conditions of low to medium cognitive load, while the opposite hold true under high cognitive load.The first study in this research found that neural efficiency emerges only when lower and higher intelligent persons work on tasks with the same objective level of difficulty, but not when tasks are matched to participants cognitive ability. This indicates that neural efficiency reflects an (ability-dependent) adaption of brain activation to the respective task demands.In a second study, we investigated differences in fiber tract (white matter) integrity with respect to intelligence. We found that, especially in men, intelligence is related to the integrity of white matter in the corpus callosum; a large bundle connecting the left and right hemispheres. This result corroborates the notion of white matter integrity for efficient information processing.While the aforementioned studies dealt with neurophysiological and -structural correlates of intelligence, the third study took an experimental approach to understanding intelligence: By means of using transcranial alternating current stimulation, we could significantly increase intelligence test performance in healthy subjects. This transient increase in cognitive performance was accompanied by a characteristic pattern of reduced activation that again underpins the neural efficiency hypothesis.Taken together, the studies conducted in the course of this research project substantiate the notion of human intelligence as efficient information processing. Additionally, we also conducted several studies on human creativity, which is increasingly recognized as a central driving force of the progress of human civilization. Most importantly, our research helped to better understand the intersections and boundaries between intelligence and creativity.