Cees J van Leeuwen

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Brain structure and dynamics are interdependent through processes such as activity-dependent neuroplasticity. In this study, we aim to theoretically examine this interdependence in a model of spontaneous cortical activity. To this end, we simulate spontaneous brain dynamics on structural connectivity networks, using coupled nonlinear maps. On slow time(More)
Our first review article (Wagemans et al., 2012) on the occasion of the centennial anniversary of Gestalt psychology focused on perceptual grouping and figure-ground organization. It concluded that further progress requires a reconsideration of the conceptual and theoretical foundations of the Gestalt approach, which is provided here. In particular, we(More)
According to a widely cited finding by Ellis and Stark (1978 Perception 7 575-581), the duration of eye fixations is longer at the instant of perceptual reversal of an ambiguous figure than before or after the reversal. However, long fixations are more likely to include samples of an independent random event than are short fixations. This sampling bias(More)
Perceiving the affordance of a tool requires the integration of several complementary relationships among actor, tool, and target. Highers order affordance structures are introduced to deal with these forms of complex action from an ecological-realist point of view. The complexity of the higher order affordance structure was used to predict the difficulty(More)
Phase patterns of human scalp alpha EEG activity show spontaneous transitions between different globally phase-synchronized states. We studied the dynamical properties of these transitions using the method of symbolic dynamics. We found greater predictability (deterministicity) and heterogeneity in the dynamics than what was expected from corresponding(More)
Effects of venlafaxine, an antidepressant acting by selective serotonin and norepinephrine reuptake inhibition with a potency ratio of 5:1, were assessed in a standardized, actual driving test, a battery of psychomotor tests (Critical Flicker/Fusion Frequency, Critical Tracking, Divided Attention), and a 45-minute vigilance test (Mackworth Clock).(More)
A figure combination task, in which three components are combined into an object, was administered under imagery-alone and externalization conditions to subjects with different levels of sketching expertise. In externalization conditions the imaged combinations were sketched. In accordance with earlier studies, the combinations were rated equally creative(More)
Stroop and Garner interference were studied in two experiments involving stimuli with several irrelevant features. Using these stimuli, which were more complex than those usually used in perceptual interference studies, a new phenomenon occurred: Stroop effects without a corresponding Garner interference were obtained in four out of six nontarget(More)
We investigate patterns of collective phase synchronization in brain activity in awake, resting humans with eyes closed. The alpha range of human electroencephalographic activity is characterized by ever-changing patterns, with strong fluctuations in both time and overall level of phase synchronization. The correlations of these patterns are reflected in(More)
We investigated the relationship between visual experience and temporal intervals of synchronized brain activity. Using high-density scalp electroencephalography, we examined how synchronized activity depends on visual stimulus information and on individual observer sensitivity. In a perceptual grouping task, we varied the ambiguity of visual stimuli and(More)