Hemispheric specialization for spatial frequency processing in the analysis of natural scenes

Experimental data coming from visual cognitive sciences suggest that visual analysis starts with a parallel extraction of different visual attributes at different scales/frequencies. Neuropsychological and functional imagery data have suggested that each hemisphere (at the level of temporo-parietal junctions-TPJ) could play a key role in spatial frequency processing: The right TPJ should predominantly be involved in low spatial frequency (LFs) analysis and the left TPJ in high spatial frequency (HFs) analysis. Nevertheless, this functional hypothesis had been inferred from data obtained when using the hierarchical form paradigm, without any explicit spatial frequency manipulation per se. The aims of this research are (i) to investigate, in healthy subjects, the hemispheric asymmetry hypothesis with an explicit manipulation of spatial frequencies of natural scenes and (ii) to examine whether the 'precedence effect' (the relative rapidity of LFs and HFs processing) depends on the visual field of scene presentation or not. For this purpose, participants were to identify either non-filtered or LFs and HFs filtered target scene displayed either in the left, central, or right visual field. Results showed a hemispheric specialization for spatial frequency processing and different 'precedence effects' depending on the visual field of presentation.     

Orbital prefrontal cortex and guidance of instrumental behavior of rats by visuospatial stimuli predicting reward magnitude

The orbital prefrontal cortex (OPFC) is part of a circuitry mediating the perception of reward and the initiation of adaptive behavioral responses. We investigated whether the OPFC is involved in guidance of the speed of instrumental behavior by visuospatial stimuli predictive of different reward magnitudes. Unoperated rats, sham-lesioned rats, and rats with bilateral lesions of the OPFC by N-methyl-D-aspartate (NMDA) were trained in a visuospatial discrimination task. The task required a lever press on the illuminated lever of two available to obtain a food reward. Different reward magnitudes were permanently assigned to lever presses to respective sides of the operant chamber; that is, responses to one lever (e.g., the left one) were always rewarded with one pellet and responses to the other lever with five pellets. On each trial, the position of the illuminated lever was pseudorandomly determined in advance. Results revealed that OPFC lesions did not impair acquisition of the task, as the speed of conditioned responses was significantly shorter with expectancy of a high reward magnitude. In addition, during reversal, shift and reshift of lever position–reward magnitude contingencies and under extinction conditions, performance of the OPFC-lesioned and control groups did not differ. It is concluded that the OPFC in rats might not be critical for adapting behavioral responses to changes of stimulus–reward magnitude contingencies signaled by visuospatial cues.     

Visual marking inhibits singleton capture

This paper is concerned with how we prioritize the selection of new objects in visual scenes. We present four experiments investigating the effects of distractor previews on visual search through new objects. Participants viewed a set of to-be-ignored nontargets, with the task being to search for a target in a second set, added to the first after 1000ms. This second set could contain a salient feature singleton, defined in terms of its color, orientation, or both color and orientation. When the singleton was a distractor, search was slowed relative to when there was no singleton. Search was facilitated when the singleton was a target. Interestingly, both the interference and facilitation effects were modulated when the preview shared features with the singleton. Follow-up experiments showed that this reduction of singleton effects was not due to: (i) low-level sensory aspects of the displays, (ii) increased heterogeneity in the search set in the preview condition, or (iii) color-based grouping of old and new items. Instead, we suggest that there is an inhibitory carry-over from the first to the second set of items based on feature similarity. We suggest the suppression stems from a process termed visual marking, which suppresses irrelevant visual objects in anticipation of more relevant new objects (Watson & Humphreys, 1997). The findings argue against alternative explanations such as the automatic capture by abrupt new onsets account.     

Concurrent-schedule performance in transition: changeover delays and signaled reinforcer ratios

Six pigeons were trained in experimental sessions that arranged six or seven components with various concurrent-schedule reinforcer ratios associated with each. The order of the components was determined randomly without replacement. Components lasted until the pigeons had received 10 reinforcers, and were separated by 10-s blackout periods. The component reinforcer ratios arranged in most conditions were 27:1, 9:1, 3:1, 1:1, 1:3, 1:9 and 1:27; in others, there were only six components, three of 27:1 and three of 1:27. In some conditions, each reinforcement ratio was signaled by a different red-yellow flash frequency, with the frequency perfectly correlated with the reinforcer ratio. Additionally, a changeover delay was arranged in some conditions, and no changeover delay in others. When component reinforcer ratios were signaled, sensitivity to reinforcement values increased from around 0.40 before the first reinforcer in a component to around 0.80 before the 10th reinforcer. When reinforcer ratios were not signaled, sensitivities typically increased from zero to around 0.40. Sensitivity to reinforcement was around 0.20 lower in no-changeover-delay conditions than in changeover-delay conditions, but increased in the former after exposure to changeover delays. Local analyses showed that preference was extreme towards the reinforced alternative for the first 25 s after reinforcement in changeover-delay conditions regardless of whether components were signaled or not. In no-changeover-delay conditions, preference following reinforcers was either absent, or, following exposure to changeover delays, small. Reinforcers have both local and long-term effects on preference. The former, but not the latter, is strongly affected by the presence of a changeover delay. Stimulus control may be more closely associated with longer-term, more molar, reinforcer effects.     

From Brahmanism to Buddhism

It is argued that early (canonical) Buddhism to a very considerable extent can and should be seen as reformed Brahmanism.

Speculations about cosmogony in Buddhist sÛtras can be traced back to Vedic sources, above all Rígveda 10.129 & 10.90—two hymns that play a similar fundamental role in the early Upanisads.

Like the immortal and unmanifest Brahman and the mortal and manifest Brahmā, the Buddha, as a mythological Bhagavat, also had two forms (or bodies). In his highest form he is “the profound” beyond being and non‐being, like Brahman. As a teacher, he is like Brahmâ. By suppressing mind and by getting rid of desire a Buddhist should “swim” back to the profound beyond the duality of life and death, which is also suffering. One becomes real and true by seeing the causal identity of tat and tvam, i.e. of macrocosm and microcosm. The spiritual ideals of early Buddhism are thus founded on natural philosophy.     

Ein Situierter Künstlicher Kommunikator für Konstruktionsaufgaben

A Situated Artificial Communicator for Assembly Tasks Summary. In this article we describe a Situated Artificial Communicator for assembly tasks. The main components of the system we are developing are a speech understanding module and a two-arm-robot module. The robot system can be instructed using spontaneous speech. The speech understanding module is based on Combinatory Categorial Grammar, which makes incremental and interactive speech understanding possible. The robot module is provided with multiple sensors and it masters complex assembly operations like peg-in-hole or screwing a nut into a bolt. The architecture and the underlying cognitive principles enable interactive processing that depends on the actual situation and allows the system to take advantage of redundant items of information. Due to these principles our Situated Artificial Communicator is highly robust. Zusammenfassung. In diesem Beitrag stellen wir einen Situierten Künstlichen Kommunikator vor, im vorliegenden Fall ein Robotersystem für Konstruktionsaufgaben. Das Robotersystem kann durch spontansprachliche Anweisungen gesteuert werden. Die Hauptkomponenten des Systems sind eine Sprachverstehenskomponente und eine Zwei-Arm-Roboterkomponente. Die Sprachverstehenskomponente basiert auf der Combinatory Categorial Grammar und ermöglicht eine inkrementelle und interaktive Sprachverarbeitung. Die Roboterkomponente verfügt über eine Vielzahl von Sensoren und beherrscht Montageoperationen wie Stecken und Schrauben. Durch die gewählte Architektur und die zugrundegelegten kognitiven Verarbeitungsprinzipien können Teilkomponenten des Systems der aktuellen Situation entsprechend interagieren und Informationsredundanz nutzen. Das System erhält dadurch eine hohe Robustheit.     

The dynamics of cognition: An ACT-R model of cognitive arithmetic

Zusammenfassung. Forschungsarbeiten zur Kognitiven Arithmetik untersuchen die mentale Repräsentation von Zahlen und arithmetischen Fakten sowie die kognitiven Prozesse die diese generieren, abrufen und manipulieren. Das Spannungsfeld zwischen der scheinbar einfachen formalen Struktur dieses Aufgabenbereichs und den Schwierigkeiten, die Kinder bei seiner Bewältigung haben, stellt einen einzigartigen Zugang zum Studium kognitiver Prozesse dar. Der vorliegende Beitrag präsentiert einen Erklärungsansatz der zentralen Befunde des Forschungsgebietes auf der Grundlage eines ACT-R Modells zur Lebenszeit-Simulation des Erwerbs arithmetischen Wissens. Die Anwendung der Bayesischen Lernmechanismen der ACT-R Architektur zeigen auf, wie sich diese Befunde auf die statistische Struktur des Aufgabengebiets zurückführen lassen. Aus den präzisen Vorhersagen der Simulation werden sowohl Hinweise zur Vermittlung arithmetischen Wissens abgeleitet als auch Erkenntnisse über die Architektur ACT-R selbst gewonnen. Im Rahmen einer formalen Analyse wird gezeigt, daß sich die vorgestellte Simulation als dynamisches System betrachten läßt, dessen Lernergebnis unmittelbar von Parametern der Architektur abhängt. Eine Untersuchung der Sensitivität der Parameter der Simulation belegt, daß die Werte, die zur besten Anpassung an die empirischen Daten führen, auch eine in einer optimalen Performanz resultieren. Die Implikationen dieses Ergebnis für die grundlegende Adaptivität menschlicher Kognition werden diskutiert. Abstract. Cognitive arithmetic studies the mental representation of numbers and arithmetic facts and the processes that create, access, and manipulate them. The contradiction between the apparent straightforwardness of its exact formal structure and the difficulties that every child faces in mastering it provides an important window into human cognition. An ACT-R model is proposed which accounts for the central results of the field through a single simulation of a lifetime of arithmetic learning. The use of the architecture's Bayesian learning mechanisms explains how these effects arise from the statistics of the task. Because of the precise predictions of the simulation, a number of lessons are derived concerning the teaching of arithmetic and the ACT-R architecture itself. A formal analysis establishes that the simulation can be viewed as a dynamical system whose ultimate learning outcome is fundamentally dependent upon some architectural parameters. Finally, an empirical study of the sensitivity of the simulation to its parameters determines that the values that yield the best fit to the data also provide optimal performance. The implications of these findings for the fundamental adaptivity of human cognition are discussed.     

Zur Psychotherapie der Depression

Ohne Zusammenfassung     

Empfehlungen zur Behandlungspraxis bei psychotherapeutischen Kriseninterventionen

Ohne Zusammenfassung     

On the efficiency of drawing computer-generated line stimuli: Rectangles can be faster than lines

A simple method is presented for optimizing the efficiency of drawing line stimuli in Turbo Pascal. It involves the substitution of Rectangle and Bar commands for Line commands and results in time savings of up to 90%. The savings are most consistent for horizontal lines, although some savings may also be made for vertical lines. The effects of different graphics libraries, graphics modes, and hardware configurations are discussed. The method proves especially useful in improving the spatiotemporal resolution of on-line-generated motion displays.