Common-onset visual masking in infancy: behavioral and electrophysiological evidence

Common-onset visual masking (COVM) occurs when a mask and a target have common onset but delayed offset, with the mask persisting beyond the duration of the target [Di Lollo, V., Enns, J. T., & Rensink, R. A. Competition for consciousness among visual events: The psychophysics of reentrant visual events. Journal of Experimental Psychology: General, 129, 481–507, 2000]. We report the first behavioral and electrophysiological evidence of COVM in infants. An initial behavioral study included a familiarization phase during which a visual pattern (the target) surrounded by four black dots (the mask) was flashed 15 times to the infant. In the “unmasked” condition, the mask disappeared with the target. In the “masked” condition, the mask remained on the screen after deletion of the target for a further 93 msec. During the test phase, the familiar target pattern was paired with a new pattern. Infants in the unmasked condition showed a significant familiarity preference, suggesting that they had encoded the target during familiarization, whereas those in the masked condition showed no preference, suggesting that they had not encoded the target during familiarization. In the second experiment, high-density event-related potentials were used to investigate the electrophysiological pattern of activity that accompanies COVM. Six-month-old infants viewed both masked and unmasked conditions. Electrophysiological data indicated that over posterior channels the masked condition elicited a larger amplitude positive wave around 300 msec after stimulus onset than trials in the unmasked condition

"Consciousness". Selected Bibliography 1970 - 2001

This is a bibliography of books and articles on consciousness in philosophy, cognitive science, and neuroscience over the last 30 years. There are three main sections, devoted to monographs, edited collections of papers, and articles. The first two of these sections are each divided into three subsections containing books in each of the main areas of research. The third section is divided into 12 subsections, with 10 subject headings for philosophical articles along with two additional subsections for articles in cognitive science and neuroscience. Of course the division is somewhat arbitrary, but I hope that it makes the bibliography easier to use. This bibliography has first been compiled by Thomas Metzinger and David Chalmers to appear in print in two philosophical anthologies on conscious experience (Metzinger 1995a, b). From 1995 onwards it has been continuously updated by Thomas Metzinger, and now is freely available as a PDF-, RTF-, or HTML-file. This bibliography mainly attempts to cover the Anglo-Saxon and German debates, in a non-annotated, fully formatted way that makes it easy to "cut and paste" from the original file. To a certain degree this bibliography also contains items in other languages than English and German - all submissions in other languages are welcome. Last update of current version: July 13th, 2001

Prestimulus oscillatory brain activity interacts with evoked recurrent processing to facilitate conscious visual perception.

We investigated whether prestimulus alpha-band oscillatory activity and stimulus-elicited recurrent processing interact to facilitate conscious visual perception. Participants tried to perceive a visual stimulus that was perceptually masked through object substitution masking (OSM). We showed that attenuated prestimulus alpha power was associated with greater negative-polarity stimulus-evoked ERP activity that resembled the visual awareness negativity (VAN), previously argued to reflect recurrent processing related to conscious perception. This effect, however, was not associated with better perception. Instead, when prestimulus alpha power was elevated, a preferred prestimulus alpha phase was associated with a greater VAN-like negativity, which was then associated with better cue perception. Cue perception was worse when prestimulus alpha power was elevated but the stimulus occurred at a nonoptimal prestimulus alpha phase and the VAN-like negativity was low. Our findings suggest that prestimulus alpha activity at a specific phase enables temporally selective recurrent processing that facilitates conscious perception in OSM

Learning the Meaning of the Vervet Alarm Calls using a Cognitive and Computational Model

This thesis explains how the infant vervet, Chlorocebus pygerthrus, learns the meaning of vervet alarm calls using the Learning Intelligent Distribution Agent\u27s (LIDA) perceptual learning mechanism. We consider an approch of multiple meanings which corresponds to a feeling-based meaning, an action-based meaning, and a referential meaning. The first part of simulations was performed to test the learning of the meaning of these alarm calls while the infant is attached physically to the mother. The second part of simulations was performed to study the infant\u27s understanding of these alarm calls while the infant is detached physically from the mother. The results show that a LIDA-based agent is capable to learn such multiple meanings. The agent learned in sequence the feeling-based meaning, the action-based meaning, and the referential meaning. The LIDA agent achieved a good performance of understanding. This was verified by checking the correct escape action after hearing a specific alarm call

The ins and outs of pleasure: roles and importance of hedonic value

Pagination differs from hard bound copy. Index missing from e-thesis.The focus of this thesis was the hedonic value of stimuli, which is more commonly known as pleasure or positive affect. First, the scientific meaning of hedonic value was dissected. Second, a classification identifying core causes of positive affect was created. The classification was derived from specific positive moments reported by individuals throughout a day (collected through experience sampling methodology). Seventeen triggers of positive affect were identified, which were extracted from the data rather than originating from theory. Third, affective influences on reflexive-like motor responses were investigated using an approach-avoidance task. Contrary to previous studies, approach reaction times were not speeded by highly affective stimuli. Instead, a novel non-emotional effect was found on reaction times, which could directly explain the current results, and those of previous studies, in non-affective terms. Fourth, the propagation of hedonic reactivity from pleasurable to neutral stimuli was investigated. Contrary to expectations, the evaluative conditioning procedure utilised did not exhibit a phenomenon called blocking. Instead, 'liking' spread non-selectively to all stimuli co-occurring with the source hedonic stimulus. Fifth, the positive effect of pleasure on goal-directed motivation was established: participants were found to press a food trigger harder for highly palatable snacks compared to bland snacks, even though participants were not informed about the hidden measurement of forces. Additionally, the impact of hedonic value on actual food intake was quantified with best-fit equations that predicted consumption at both the group and individual level. In the last study, hedonic habituation, or the inhibitory effect of pleasure on itself, was demonstrated: eating pleasant snacks, as compared to bland ones, reduced the hedonic ratings of test foods that were consumed afterwards. Finally, these inputs and outputs of hedonics were integrated into a model specifying principal roles of pleasure in human behaviour. This pleasure-incentive model explains the effects of pleasure on incentive motivation, and makes important predictions about the mechanisms of pathological conditions such as over-eating and drug addiction

Tuning and verifying a psychologically plausible cognitive architectureusing LIDA-based cognitive software agents

Diese Arbeit beschreibt einen Ansatz, die Plausibilität der kognitiven Architektur LIDA (Learning Intelligent Distribution Agent) zu untermauern. Zunächst wird eine Korrelation zwischen LIDA’s internen Prozessen und neuronalen Vorgängen hergestellt, und LIDA’s Parameter werden mithilfe von Daten aus publizierten neurowissenschaftlichen Untersuchungen angepasst. Außerdem wird das Modell durch zwei neuartige Komponenten erweitert, um eine größere Auswahl an kognitiven Aufgaben modellieren zu können: durch ein auf translationsinvarianter Merkmalsextraktion beruhendes visuelles Objekterkennungssystem, und durch ein Aufmerksamkeitsmodell, das auf dem Locus Coeruleus / Noradrenalin System beruht. Drei auf dem erweiterten LIDA-Modell basierende kognitive Softwareagenten werden beschrieben und ihr Verhalten mit Daten menschlicher Versuchspersonen verglichen: ein Softwareagent, der ein einfaches Reaktionszeitexperiment reproduziert; ein Agent, der ein Experiment zur Untersuchung der Wahrnehmungskontinuität bei Menschen modelliert; und schließlich ein Agent, der ein Aufmerksamkeitsblinzeln-Experiment durchführt. Die Arbeit zeigt, dass LIDA-basierte Softwareagenten fähig sind, menschliche Versuchsdaten zu reproduzieren; und unterstreicht die Plausibilität der kognitiven Architektur LIDA basierend auf der Korrelation ihrer Mechanismen und Prozessen im menschlichen Gehirn, und auf dem von den kognitiven Softwareagenten erfolgreich reproduziertem menschlichen Verhalten.This thesis describes an approach to provide evidence that the LIDA (Learning Intelligent Distribution Agent) cognitive architecture models basic human cognitive processes. The computational LIDA architecture’s processes are correlated with neural processes and its parameters are adjusted using brain-related evidence. The model is also extended by an invariant feature detection-based visual object recognition system, and a novel attentional mechanism based on a model of the locus coeruleus – norepinephrine system in the brain, to facilitate computational modeling of a wider range of cognitive tasks than was possible before. Three LIDA-based cognitive software agents are also described and compared with human behavioral data, modeling three different psychological paradigms: a simple reaction time experiment, a perceptual continuity experiment and a visual attentional blink task. The thesis shows that the LIDA-based agents are capable of accurately reproducing human data, and argues in favor of psychological - and, in most cases, also neuroscientific – plausibility of the LIDA cognitive architecture, based on the correlation of its mechanisms to processes in the human brain, and based on the successfully reproduced behavioral data falling naturally out of the same computational model, using the same parameter set