Various kinds of observations show that the ability of human beings to both consciously relive past events – episodic memory – and conceive future events, entails an active process of construction. This construction process also underpins many other important aspects of conscious human life, such as perceptions, language and conscious thinking. This article provides an explanation of what makes the constructive process possible and how it works. The process mainly relies on attentional activity, which has a discrete and periodic nature, (...) and working memory, which allows for the combination of discrete attentional operations. An explanation is also provided of how past and future events are constructed. (shrink)

Purely parallel neural networks can model object recognition in brief displays – the same conditions under which illusory conjunctions have been demonstrated empirically. Correcting errors of illusory conjunction is the “tag-assignment” problem for a purely parallel processor: the problem of assigning a spatial tag to nonspatial features, feature combinations, and objects. This problem must be solved to model human object recognition over a longer time scale. Our model simulates both the parallel processes that may underlie illusory conjunctions and the serial (...) processes that may solve the tag-assignment problem in normal perception. One component of the model extracts pooled features and another provides attentional tags that correct illusory conjunctions. Our approach addresses two questions: How can objects be identified from simultaneously attended features in a parallel, distributed representation? How can the spatial selectional requirements of such an attentional process be met by a separation of pathways for spatial and nonspatial processing? Our analysis of these questions yields a neurally plausible simulation of tag assignment based on synchronizing feature processing activity in a spatial focus of attention. (shrink)

Everybody knows the phenomena summarized with the term attention: concentration, focalization, limitation, selection, and intensification . The explanation of these phenomena is, however, a different matter. Problems easily arise with regard towhathas to be explained and with regard to thestyleof explanation. A problem of the first kind is the “methodology of ‘bad focus’”: the explanation starts with and is fixated on an intuitively striking but nonessential behavioral feature or cognitive achievement. A problem of the second kind is a “virtus dormitiva” (...) explanation: the explanation starts with emphasizing one aspect of the observed phenomena, the emphasized aspect receives an interesting and suggestive name, and that name with its connotations is used as a concept in the explanation. At the start of contemporary, behavior-based, information processing psychology, avirtus dormitivaexplanation infiltrated the functional accounts of the phenomena of attention; the empirical observation that people show performance limitations was translated into the theoretical concept of a communication channel with a limited capacity. That limited capacity notion became the core concept in what can be called the standard theory of attention. This standard theory of attention faced severe difficulties in explaining the guidance of attention by the information processor's goals and intentions. Subsequent modifications, concerned with removing these difficulties, revealed that selection, guided by goals and intentions, is the essential behavioral feature and that the observed performance limitations are a result of this selection. So, the limited capacity theorizing was not only plagued by avirtus dormitivaexplanation, it also suffered from the methodology of bad focus. (shrink)

In this study, voluntary and involuntary visual attention focused on different interpretations of a bistable image, were investigated using magnetoencephalography. A Necker cube with sinusoidally modulated pixels' intensity in the front and rear faces with frequencies 6.67 Hz and 8.57 Hz, respectively, was presented to 12 healthy volunteers, who interpreted the cube as either left- or right-oriented. The tags of these frequencies and their second harmonics were identified in the average Fourier spectra of the MEG data recorded from the visual (...) cortex. In the first part of the experiment, the subjects were asked to voluntarily control their attention by interpreting the cube orientation as either being on the left or right. Accordingly, we observed the dominance of the corresponding spectral component, and voluntary attention performance was measured. In the second part of the experiment, the subjects were asked to focus their gaze on a red marker at the center of the cube image without putting forth effort in its interpretation. The alternation of the dominant spectral energies at the second harmonics of the stimulation frequencies was treated as changes in the cube orientation. Based on the results of the first experimental stage and using a wavelet analysis, we developed a method which allowed us to identify the currently perceived cube orientation. Finally, we characterized involuntary attention using the distribution of dominance times when focusing attention on one of the cube orientations, which was related to voluntary attention performance and brain noise. In particular, we confirmed our hypothesis that higher attention performance is associated with stronger brain noise. (shrink)