n-Variable Bisection

This paper deals with the measurement problem of deriving an overall evaluation of stimuli by n-component bisection. Reflexivity and a generalised form of bisymmetry for two variables will be shown to characterise n-component bisection in terms of quasilinear means, unique up to linear transformations of their generating functions. Copyright 2000 Academic Press.     

A neuro-cognitive visual system for object recognition based on testing of interactive attentional top-down hypotheses

We propose an extension of a systemic model for object recognition formulated by Rybak et al (1998 Vision Research 38 2387-2400) which is based on the functional organisation of the visual systems in primate brains. In contrast to the learning and recognition scheme of Rybak et al we do not assume a behavioural paradigm, i.e. a visuomotor programmed scanpath that determines the sequence of foveation on the different parts of the object. As in the basis architecture of Rybak et al, the system modules are separated into 'what'-like subsystems corresponding to the ventral occipito-inferotemporal visual path and 'where'-like complexes analogous to the dorsal occipito-parietal visual path. The 'what' system analyses local features in the actual foveation as in Rybak et al. But, in our case, the 'where' memory, instead of programming a behavioural scanpath, scores the spatial relationship between successive fixation and the spatial relationship between the associated main edges. The recognition is based on the identification of parts and their spatial relationship. This gives the learning and recognition mechanisms more flexibility in the sense that, for recognising an object, several different fixation sequences may be accepted.     

Development of object permanence in food-storing magpies (Pica pica)

The development of object permanence was investigated in black-billed magpies (Pica pica), a food-storing passerine bird. The authors tested the hypothesis that food-storing development should be correlated with object-permanence development and that specific stages of object permanence should be achieved before magpies become independent. As predicted, Piagetian Stages 4 and 5 were reached before independence was achieved, and the ability to represent a fully hidden object (Piagetian Stage 4) emerged by the age when magpies begin to retrieve food. Contrary to psittacine birds and humans, but as in dogs and cats, no "A-not-B error" occurred. Although magpies also mastered 5 of 6 invisible displacement tasks, evidence of Piagetian Stage 6 competence was ambiguous.     

Neubewertung kognitiver Leistungen im Lichte der F?higkeiten einzelliger Lebewesen

A closer look at unicellular organisms and their behavior as autonomous and social beings sheds new light on the nature of cognition. This allows, at the same time, a search for minimal conditions that help to identify the yet unknown appearance of cognition during evolution. Positive results might also serve as principles for the construction of intelligent artefacts as striven for in artificial intelligence and cognitive robotics research. Analyzing the abilities of prokaryotes and unicellular eukaryotes and comparing them to the abilities of "higher" organisms, we conclude that common definitions of cognition are not specific enough. The attempt to define cognition by focusing on the coupling between stimulus and response and asserting that (to have cognition) it has to be indirect and modifiable fails, simply because in all organisms every reaction to a stimulus is indirect and modifiable. A definition of cognition based on such a distinction cannot hold unless one is willing to ascribe cognitive capacities also to Escherichia coli bacteria, for instance. Viewing cognition as the sum of abilities necessary for coping with a complex physical and social environment is also highly questionable, i.e. unspecific. We show that functions comparable to the cognitive functions "perception" and "memory" in higher organisms can well be identified in unicellular beings. The "architecture" of the bacterial (prokaryotic) sensorimotor apparatus is also in some structures, but particularly at the functional level, comparable with that of higher organisms and should be, as a consequence, indicative of cognition. Furthermore, we discuss other, somewhat more delimitable, phenomena like detection of identity, counting, adaptation, habituation and learning in ethological categories and compare them to findings from the microorganismic world. In this context, we argue that so-called "true learning" and the appearance of nervous systems are not break-points in the evolution of cognition. The presence of nervous systems means only a huge amplification of the recognition power of individual organisms. The molecular net that realizes the regulation and transduction of signals in unicellular beings is comparable to the processes within a neural net, and a population of unicellular organisms can be viewed as an individual, multicellular net with amplified recognition power. Finally, we show that sophisticated forms of cooperation and competition developed also in populations of unicellular organisms. This seems not to be true for the phenomena imagination (rehearsal) and introspection, also to be seen as stemming from social problem-solving needs. As for these aspects, further research is needed, however, to put them on firm scientific grounds. Zusammenfassung. Eine genaue Betrachtung einzelliger Lebewesen und ihres Verhaltens als autonome und soziale Wesen wirft neues Licht auf die Natur von Kognition. Das erlaubt gleichzeitig eine Suche nach minimalen Bedingungen, die bei der Bestimmung des Erscheinens von Kognition in der Evolution helfen. Positive Ergebnisse könnten auch als Prinzipien für die Konstruktion intelligenter Artefakte dienen, wie sie in der Künstlichen Intelligenz und der kognitiven Robotikforschung angestrebt werden. Ein Vergleich der Fähigkeiten von Einzellern mit denen von "höheren" Organismen führt uns zu dem Schluß, daß gängige Definitionen von Kognition nicht spezifisch genug sind. Der Versuch, Kognition über die Indirektheit und Modifizierbarkeit der Kopplung zwischen Reiz und Reaktion zu definieren, scheitert, weil in allen Organismen Reiz-Reaktionsverbindungen indirekt und modifizierbar sind. Eine solche Definition ist nicht haltbar, es sei denn, man ist bereit, z.B. auch Escherichia coli-Bakterien kognitive Eigenschaften zuzubilligen. Die Definition von Kognition als Summe der Eigenschaften, die notwendig sind, um in einer komplexen physikalischen und sozialen Umgebung zu bestehen, ist ebenfalls hinterfragbar und unspezifisch. Wir zeigen, daß Leistungen, die mit den Kognitionsleistungen "Wahrnehmung" und "Gedächtnis" in höheren Organismen vergleichbar sind, in Einzellern nachweisbar sind. Die sensomotorische Komplexität von Einzellern ist auch in vieler Hinsicht strukturell, vor allem aber funktionell vergleichbar mit derjenigen höherer Organismen und kann deshalb als ein Hinweis auf Kognition gewertet werden. Darüber hinaus diskutieren wir andere, abgrenzbare Phänomene, wie Erfassung von Identität, Zählen, Adaptation, Habituation und Lernen, aus der Sicht der Verhaltensforschung und vergleichen sie mit Befunden aus der Welt der Mikroorganismen. In diesem Zusammenhang bestreiten wir, daß sogenanntes "echtes Lernen" und das Erscheinen von Nervensystemen Bruchstellen in der Evolution von Kognition sind. Die Anwesenheit von Nervensystemen bedeutet nur den Übergang von Systemen mit einem relativ begrenzten (Erkennungs-) Potential zu solchen mit einem riesigen Potential. Das molekulare Netz, das die Regulation und Transduktion von Signalen in Einzellern realisiert, ist vergleichbar mit den Prozessen innerhalb eines Nervennetzes. Eine Population von einzelligen Organismen kann als individuelles, multizelluläres Netz mit erhöhtem Erkennungspotential angesehen werden. Schließlich zeigen wir, daß raffinierte Formen von Kooperations- und Konkurrenzverhalten auch in Einzellerpopulationen vorhanden sind. Eine ähnliche Aussage scheint nicht für Phänomene wie Imagination (Probehandeln) und Introspektion möglich zu sein, die auch im Zusammenhang mit der Bewältigung sozialer Probleme zu sehen sind. Eine genaue naturwissenschaftliche Erfassung solcher Aspekte, die erst einen Vergleich zwischen Mehrzellern und Einzellern erlauben würde, ist allerdings noch zu leisten.     

Psychophysical isolation of the modality responsible for detecting multimodal stimuli: a chemosensory example

Multiple sense modalities can be stimulated conjointly by a physically complex item, such as a predator, and also by a physically solitary stimulus that acts on multiple receptor classes. As a prime example of this latter group, l-menthol from mint stimulates taste, smell, and several somatosensory submodalities. In 6 experiments that used a variety of psychometric techniques, the authors experimentally isolated the modality by which l-menthol is detected in the upper airways (the nose and mouth). Interestingly, absolute detection in both the nasal and oral cavities was based on olfaction and not stinging, cooling, or taste. These experiments illustrate how the sensory modality responsible for detecting a multimodal or multisensory stimulus can be psychophysically isolated.     

Action comprehension: deriving spatial and functional relations

A perceived action can be understood only when information about the action carried out and the objects used are taken into account. It was investigated how spatial and functional information contributes to establishing these relations. Participants observed static frames showing a hand wielding an instrument and a potential target object of the action. The 2 elements could either match or mismatch, spatially or functionally. Participants were required to judge only 1 of the 2 relations while ignoring the other. Both irrelevant spatial and functional mismatches affected judgments of the relevant relation. Moreover, the functional relation provided a context for the judgment of the spatial relation but not vice versa. The results are discussed in respect to recent accounts of action understanding.     

Detection of sound rise time by adults with dyslexia

Low sensitivity to amplitude modulated (AM) sounds is reported to be associated with dyslexia. An important aspect of amplitude modulation cycles are the rise and fall times within the sound. In this study, simplified stimuli equivalent to just one cycle were used and sensitivity to varying rise times was explored. Adult participants with dyslexia or compensated dyslexia and a control group performed a detection task with sound pairs of different rise times. Results showed that the participants with dyslexia differed from the control group in rise time detection and a correlation was found between rise time detection and reading and phonological skills. A subgroup of participants with lower sensitivity to rise time detection characterized by low accuracy in syllable-level phonological skills was found within the dyslexic group. Short stimuli containing only one rise time produced associations with phonological skills and reading, even in a language where the perception of rise time contrasts are not crucial for the signaling of phonemic contrast.     

Determinants of stress-related growth: Gender,stressfulness of the event,and coping strategies

The present study aimed to investigate the determinants of stress-related growth. For this aim the associations of gender, stressfulness of the event, and three coping strategies (problem-oriented, fatalistic, and helplessness) with stress-related growth were tested by multiple regression analysis. Participants were 132 undergraduate students. Results revealed that females reported higher levels of stress-related growth than males, and as expected, higher levels of the stressfulness of the event associated with more stress-related growth. Furthermore, frequent utilization of problem-oriented and fatalistic coping strategies was associated with higher stress-related growth. These findings were discussed in the light of relevant literature and culture-specific features. This work has been supported by the Turkish Academy of Sciences, in the framework of the Young Scientist Award Program (TG-TUBA-GEB>P/2002-l-l 1).