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PubMed1989

Comparative physiology and biochemistry: challenges for the future.

1. Comparative physiology is distinguished from other types of physiology by treating the diversity of solutions of functional problems and by using kind of animal as a functional variable. 2. The strength of comparative physiology os its capacity to give some solutions to problems in basic biology. 3. Specific examples of subject areas to which comparative physiology contributes are: (a) mechanisms underlying evolution; (b) the nature of speciation; (c) comparative cognitive science, neural models for behavior; and (d) applications of molecular techniques to physiology of whole animals. 4. Applications continue in ecology, medicine and agriculture. 5. The breadth of the comparative approach to physiology has important philosophical implications.

Animals↗
PubMed2005

The effect of visuo-motor transformations on hand-foot coordination: evidence in favor of the incongruency hypothesis.

Understanding how multiple constraints contribute to the emergence of coordinated behavior has been the topic of considerable debate in cognitive sciences. The present experiment addressed the issue of the effects of visual motion structures (iso- and non-isodirectionality) on the stability of hand-foot coordination patterns. Visuo-motor transformations--decorrelating the perceived movement direction from the actually generated direction--were applied to both in-phase and anti-phase patterns. Two mutually exclusive hypotheses--the "visual grouping hypothesis" and the "incongruency hypothesis"--were tested. The results indicated that both conditions of transformed visual feedback destabilized the actual performed coordination patterns. Thus, despite the existence of common underlying principles that govern both the perceived motion pattern and the generation of hand-foot coordination patterns, it appeared that perceptual grouping principles were not exploited to monitor the production of coordination. These results strongly suggest that the congruency between the performed pattern and the perceived visual feedback is the primary factor determining the (in)stability of hand-foot coordination patterns.

Adult↗
PubMed2006

The attentional blink reveals sluggish attentional shifting in adolescents with specific language impairment.

Rapid processing deficits have been the subject of much debate in the literature on specific language impairment (SLI). Hari and Renvall (2001) [Hari, R. & Renvall, H. (2001). Impaired processing of rapid stimulus sequences in dyslexia. Trends in cognitive sciences, 5, 525-532.] proposed that the source of this deficit can be attributed to sluggish attentional shifting abilities. That is, more time is required to shift attention between stimuli. To test this claim, 26 adolescents with SLI (divided into two subgroups to control for differences in non-verbal intelligence) and 14 controls were presented with a rapid serial visual presentation task. In this task participants were asked to detect two visual targets presented serially with distracter items with varying inter-target intervals (i.e., time difference between targets). This task was designed to elicit an attentional blink (AB). The AB describes the phenomenon whereby non-impaired individuals are less likely to report the second of two targets presented within 200-500ms of each other. After controlling for group differences in non-verbal intelligence, the SLI group was found to be significantly less accurate than the control group at successfully reporting the second target at inter-target intervals of 100, 200, 300, 400 and 800ms. The results were interpreted to suggest that adolescents with language impairments have an AB which differs from non-impaired individuals in both magnitude and duration.

Adolescent↗
PubMed2005

Lower frequency variability in the alpha activity in EEG among patients with epilepsy.

OBJECTIVE: Clinically, intra-subject variability of the alpha frequency is well known, but sparsely documented and practically not used in the evaluation of the electroencephalogram (EEG). In cognitive science, however, the peak alpha frequency (PAF) variations are implemented. The aim of the present study was to document the clinical notion of differences in alpha frequency variations in patients with epilepsy compared to a control group. METHODS: Standard EEG recordings from 28 patients, 18 with epilepsy and 10 patients having EEG for other reasons were included. Ten seconds of artifact free EEG were sampled from F3, F4, T5, T6, O1 and O2 at the beginning, after hyperventilation and at the end of a 20 m recording and Fast Fourier transforms was applied to these epochs of each recording. RESULTS: The study showed a lower frequency in the epilepsy group (frontal 9.22 vs. 10.24 Hz, temporal 9.18 vs. 9.88 Hz and occipital 9.42 vs. 10.30 Hz) and lower frequency variability, with lower values in the epilepsy group in occipital (0.8 vs. 1.44 Hz) and temporal leads (0.89 vs. 1.39 Hz). Frontally, the variability was not significant (0.71 vs. 1.18 Hz, P = 0.0824). Within the groups, there was no relation between frequency and variability. CONCLUSIONS: This study shows that there is PAF variability in the alpha activity. This variability is compromised in patients with epilepsy. Lower alpha frequency is observed in epilepsy group. It is to some extent due to antiepileptic drugs. The lower alpha frequency variability is probably due to a different mechanism as there is no relation between the frequency and its variability within the two groups. SIGNIFICANCE: The alpha activity shows physiological frequency variations that may be compromised by epilepsy.

Adult↗
PubMed2006

Why stereotypes don't even make good defaults.

Many concepts have stereotypes. This leaves open the question of whether concepts are stereotypes. It has been argued elsewhere that theories that identify concepts with their stereotypes or with stereotypical properties of their instances (e.g., Rosch, E. (1978). Principles of categorization. In E. Rosch & B. B. Lloyd (Ed.), Cognition and Categorization. Hillsdale, NJ: Lawrence Erlbaum Associates; Smith, E. E., Medin, D. L. (1981). Categories and Concepts. Cambridge, MA: Harvard University Press.) fail to provide an adequate account of the compositionality of concepts (Fodor, J., Lepore, E. (1996). The red herring and the pet fish: Why concepts still cannot be prototypes. Cognition, 58, 253-270.; Fodor, J. (1998). Concepts: Where cognitive science went wrong. New York, NY: Oxford University Press.). This paper extends this argument and reports an experiment suggesting that participants do not assume, even as a default strategy, that complex concepts inherit the stereotypes of their constituents. Thus propositions such as "Baby ducks have webbed feet" were judged to be less likely to be true than propositions like "Ducks have webbed feet." Moreover, manipulation of the type and number of noun phrase modifiers revealed a systematic departure from the unmodified noun's stereotype both with the addition of stereotypical modifiers ("Quacking ducks have webbed feet" versus "Ducks have webbed feet") and with the addition of a second modifier ("Baby Peruvian ducks have webbed feet" versus "Baby ducks have webbed feet"). Thus, in the general case the stereotypical properties of a head noun are systematically discounted when that head noun combines with modifiers. This effect represents a general principle of conceptual combination that argues against the inheritance of stereotypical features of concepts as a default strategy. Instead, we advocate a model of conceptual combination where concepts remain inert under combination, supported by a separate machinery that introduces pragmatic and knowledge-dependent inferences.

Adult↗
PubMed2004

Heuristic evaluation of infusion pumps: implications for patient safety in Intensive Care Units.

OBJECTIVE: The goal of this research was to use a heuristic evaluation methodology to uncover design and interface deficiencies of infusion pumps that are currently in use in Intensive Care Units (ICUs). Because these infusion systems cannot be readily replaced due to lease agreements and large-scale institutional purchasing procedures, we argue that it is essential to systematically identify the existing usability problems so that the possible causes of errors can be better understood, passed on to the end-users (e.g., critical care nurses), and used to make policy recommendations. DESIGN: Four raters conducted the heuristic evaluation of the three-channel infusion pump interface. Three raters had a cognitive science background as well as experience with the heuristic evaluation methodology. The fourth rater was a veteran critical care nurse who had extensive experience operating the pumps. The usability experts and the domain expert independently evaluated the user interface and physical design of the infusion pump and generated a list of heuristic violations based upon a set of 14 heuristics developed in previous research. The lists were compiled and then rated on the severity of the violation. RESULTS: From 14 usability heuristics considered in this evaluation of the Infusion Pump, there were 231 violations. Two heuristics, "Consistency" and "Language", were found to have the most violations. The one with fewest violations was "Document". While some heuristic evaluation categories had more violations than others, the most severe ones were not confined to one type. The Primary interface location (e.g., where loading the pump, changing doses, and confirming drug settings takes place) had the most occurrences of heuristic violations. CONCLUSION: We believe that the Heuristic Evaluation methodology provides a simple and cost-effective approach to discovering medical device deficiencies that affect a patient's general well being. While this methodology provides information for the infusion pump designs of the future, it also identifies important insights concerning equipment that is currently in use in critical care environments.

Humans↗
PubMed2006

Recursive causality in evolution: a model for epigenetic mechanisms in cancer development.

Interactions between adaptative and selective processes are illustrated in the model of recursive causality as defined in Rupert Riedl's systems theory of evolution. One of the main features of this theory also termed as theory of evolving complexity is the centrality of the notion of 'recursive' or 'feedback' causality - 'the idea that every biological effect in living systems, in some way, feeds back to its own cause'. Our hypothesis is that "recursive" or "feedback" causality provides a model for explaining the consequences of interacting genetic and epigenetic mechanisms which are known to play a key role in development of cancer. Epigenetics includes any process that alters gene activity without changes of the DNA sequence. The most important epigenetic mechanisms are DNA-methylation and chromatin remodeling. Hypomethylation of so-called oncogenes and hypermethylation of tumor suppressor genes appear to be critical determinants of cancer. Folic acid, vitamin B12 and other nutrients influence the function of enzymes that participate in various methylation processes by affecting the supply of methyl groups into a variety of molecules which may be directly or indirectly associated with cancerogenesis. We present an example from our own studies by showing that vitamin D3 has the potential to de-methylate the osteocalcin-promoter in MG63 osteosarcoma cells. Consequently, a stimulation of osteocalcin synthesis can be observed. The above mentioned enzymes also play a role in development and differentiation of cells and organisms and thus illustrate the close association between evolutionary and developmental mechanisms. This enabled new ways to understand the interaction between the genome and environment and may improve biomedical concepts including environmental health aspects where epigenetic and genetic modifications are closely associated. Recent observations showed that methylated nucleotides in the gene promoter may serve as a target for solar UV-induced mutations of the p53 tumor suppressor gene. This illustrates the close interaction of genetic and epigenetic mechanisms in cancerogenesis resulting from changes in transcriptional regulation and its contribution to a phenotype at the micro- or macroevolutionary level. Above-mentioned interactions of genetic and epigenetic mechanisms in oncogenesis defy explanation by plain linear causality, things like the continuing adaptability of complex systems. They can be explained by the concept of recursive causality and has introduced molecular biology into the realm of cognition science and systems theory: based on the notion of so-called feedback- or recursive causality a model for epigenetic mechanisms with relevance for oncology and biomedicine is provided.

Animals↗
PubMed2006

Dynamic imaging with MRI contrast agents: quantitative considerations.

Time-resolved MRI has had enormous impact in cognitive science and may become a significant tool in basic biological research with the application of new molecular imaging agents. In this paper, we examine the temporal characteristics of MRI contrast agents that could be used in dynamic studies. We consider "smart" T1 contrast agents, T2 agents based on reversible aggregation of superparamagnetic nanoparticles and sensors that produce changes in saturation transfer effects (chemical exchange saturation transfer, CEST). We discuss response properties of several agents with reference to available experimental data, and we develop a new theoretical model that predicts the response rates and relaxivity changes of aggregation-based sensors. We also perform calculations to define the extent to which constraints on temporal resolution are imposed by the imaging methods themselves. Our analysis confirms that some small T1 agents may be compatible with MRI temporal resolution on the order of 100 ms. Nanoparticle aggregation T2 sensors are applicable at much lower concentrations, but are likely to respond on a single second or slower timescale. CEST agents work at high concentrations and temporal resolutions of 1-10 s, limited by a requirement for long presaturation periods in the MRI pulse sequence.

Brain Mapping↗
PubMed2006

Organization of the state space of a simple recurrent network before and after training on recursive linguistic structures.

Recurrent neural networks are often employed in the cognitive science community to process symbol sequences that represent various natural language structures. The aim is to study possible neural mechanisms of language processing and aid in development of artificial language processing systems. We used data sets containing recursive linguistic structures and trained the Elman simple recurrent network (SRN) for the next-symbol prediction task. Concentrating on neuron activation clusters in the recurrent layer of SRN we investigate the network state space organization before and after training. Given a SRN and a training stream, we construct predictive models, called neural prediction machines, that directly employ the state space dynamics of the network. We demonstrate two important properties of representations of recursive symbol series in the SRN. First, the clusters of recurrent activations emerging before training are meaningful and correspond to Markov prediction contexts. We show that prediction states that naturally arise in the SRN initialized with small random weights approximately correspond to states of Variable Memory Length Markov Models (VLMM) based on individual symbols (i.e. words). Second, we demonstrate that during training, the SRN reorganizes its state space according to word categories and their grammatical subcategories, and the next-symbol prediction is again based on the VLMM strategy. However, after training, the prediction is based on word categories and their grammatical subcategories rather than individual words. Our conclusion holds for small depths of recursions that are comparable to human performances. The methods of SRN training and analysis of its state space introduced in this paper are of a general nature and can be used for investigation of processing of any other symbol time series by means of SRN.

Artificial Intelligence↗
PubMed2005

Neural correlates of intelligence as revealed by fMRI of fluid analogies.

It has been conjectured that the cognitive basis of intelligence is the ability to make fluid or creative analogical relationships between distantly related concepts or pieces of information (Hofstadter, D.R. 1995. Fluid Concepts and Creative Analogies. Basic Books, New York., Hofstadter, D.R. 2001. Analogy as the Core of Cognition. In The Analogical Mind: Perspectives from Cognitive Science (D. Gentner, K. J. Holyoak and B. N. Kokinov, Ed.). pp. 504-537. MIT Press, Cambridge, Mass.). We hypothesised that fluid analogy-making tasks would activate specific regions of frontal cortex that were common to those of previous inferential reasoning tasks. We report here a novel self-paced event-related fMRI study employed to investigate the neural correlates of intelligence associated with undertaking fluid letter string analogy tasks. Stimuli were adapted from items of the AI program Copycat (Mitchell, M. 1993. Analogy-making as Perception: A computer model. The MIT Press, Cambridge MA.). Twelve right-handed adults chose their own "best" completions from four plausible response choices to 55 fluid letter string analogies across a range of analogical depths. An analysis using covariates determined per subject by analogical depth revealed significant bilateral neural activations in the superior, inferior, and middle frontal gyri and in the anterior cingulate/paracingulate cortex. These frontal areas have been previously associated with reasoning tasks involving inductive syllogisms, syntactic hierarchies, and linguistic creativity. A higher-order analysis covarying participants' verbal intelligence measures found correlations with individual BOLD activation strengths in two ROIs within BA 9 and BA 45/46. This is a provocative result given that verbal intelligence is conceptualised as being a measure of crystallised intelligence, while analogy making is conceptualised as requiring fluid intelligence. The results therefore support the conjecture that fluid analogising could underpin general intellectual performance.

Adolescent↗
PubMed2003

Measuring word recognition in reading: eye movements and event-related potentials.

The investigation of visual word recognition has been a major accomplishment of cognitive science. Two on-line methodologies, eye movements and event-related potentials, stand out in the search for the holy grail - an absolute time measure of when, how and why we recognize visual words while reading. Although each technique has its own experimental limitations, we suggest, by means of review and comparison, that these two methodologies can be used in complementary ways to produce a better picture of the mental action we call reading.

Journal Article↗
PubMed2004

Argument structure and the child's contribution to language learning.

One of the oldest questions in cognitive science asks whether children are able to learn language (or anything) because they are equipped with a very powerful general-purpose learning mechanism or because they are equipped with a domain-specific constrained language acquisition device. Recent advances in statistical approaches to language learning seem to boost the plausibility of general-purpose learning. However, in this article we propose that in the domain of verb learning, children rely more on their internally generated preconceptions about linguistic structure than on robust cues in the input, suggesting that at least in this aspect of language learning, domain-specific grammatical knowledge guides linguistic development.

Adolescent↗
PubMed2005

Absolute pitch: perception, coding, and controversies.

Recent findings in cognitive neuroscience and cognitive psychology are converging to shed light on the nature of processing, categorization and memory for pitch in humans and animals. Although most people are unable to name or place pitch values in consistent, well-defined categories, as they do for color, stable long-term memory for pitch has been shown in certain animal species, in infants, and in both adult musicians and non-musicians. 'Absolute pitch', the rare ability to label pitches without external reference, appears to require acquisition early in life, and involves specialized brain mechanisms, now partially identified. Research on pitch coding strategies informs wider theories in cognitive science of semantic memory, and the nature of perceptual categories.

Animals↗
PubMed2006

Vision as Bayesian inference: analysis by synthesis?

We argue that the study of human vision should be aimed at determining how humans perform natural tasks with natural images. Attempts to understand the phenomenology of vision from artificial stimuli, although worthwhile as a starting point, can lead to faulty generalizations about visual systems, because of the enormous complexity of natural images. Dealing with this complexity is daunting, but Bayesian inference on structured probability distributions offers the ability to design theories of vision that can deal with the complexity of natural images, and that use 'analysis by synthesis' strategies with intriguing similarities to the brain. We examine these strategies using recent examples from computer vision, and outline some important implications for cognitive science.

Algorithms↗
PubMed2001

Phonology competes with syntax: experimental evidence for the interaction of word order and accent placement in the realization of Information Structure.

In this paper, we investigate the interaction of phonological and syntactic constraints on the realization of Information Structure in Greek, a free word order language. We use magnitude estimation as our experimental paradigm, which allows us to quantify the influence of a given linguistic constraint on the acceptability of a sentence. We present results from two experiments. In the first experiment, we focus on the interaction of word order and context. In the second experiment, we investigate the additional effect of accent placement and clitic doubling. The results show that word order, in contrast to standard assumptions in the theoretical literature, plays only a secondary role in marking the Information Structure of a sentence. Order preferences are relatively weak and can be overridden by constraints on accent placement and clitic doubling. Our experiments also demonstrate that a null context shows the same preference pattern as an all focus context, indicating that 'default' word order and accent placement (in the absence of context) can be explained in terms of Information Structure. In the theoretical part of this paper, we formalize the interaction of syntactic and phonological constraints on Information Structure. We argue that this interaction is best captured using a notion of grammatical competition, such as the one developed by Optimality Theory (Prince & Smolensky, 1993, Optimality theory: constraint interaction in generative grammar (Technical Report No. 2). Center for Cognitive Science, Rutgers University, Piscataway, NJ; Science 275 (1997) 1604). In particular, we exploit the optimality theoretic concept of constraint ranking to account for the fact that some constraint violations are more serious than others. We extend standard Optimality Theory to obtain a grammar model that predicts not only the optimal (i.e. grammatical) realization of a given input, but also makes predictions about the relative grammaticality of suboptimal structures. This allows us to derive a constraint hierarchy that accounts for the interaction of phonological and syntactic constraints on Information Structure and models the acceptability patterns found in the experimental data.

Adult↗
PubMed2002

Names, concepts, features and the living/nonliving things dissociation.

The present paper evaluates different hypotheses for explaining the living/nonliving things dissociation phenomenon in terms of feature type, considering the role of this dimension in the organization of conceptual semantic representations and in the activation of name representations. For this purpose we used Sloman and associates' (Memory and Cognition 27(3) (1999) 526; Cognitive Science 22(2) (1998) 189) name centrality and conceptual centrality tasks and asked subjects to judge functional and perceptual/visual features of living and nonliving items. Conceptual centrality results are more in accordance with a "single feature-domain connection hypothesis" where visual features are more important than functional features for the representation of living things and no feature type advantage is found for nonliving things. Name centrality results show that functional features are more important than sensory/visual features overall, a result that is not predicted by any of the hypotheses considered. The fact that the two judgments diverge emphasizes their importance for evaluating the role of feature type in the living/nonliving dissociation. Implications for explaining this phenomenon are also discussed.

Concept Formation↗
PubMed2003

Differential effect of distractor timing on localizing versus identifying visual changes.

When visual changes are accompanied by visual transients, such as in the case of saccades, eye blinks, and brief flickers, they often go unnoticed; this phenomenon is called change blindness (Rensink, R. A. (2002). Change detection. Annual Review of Psychology 53, 245; Simons, D. J., & Levin, D. T. (1997). Change blindness. Trends in Cognitive Sciences 1, 261). Change blindness occurs even when the position of visual transients does not cover the location of the change (as in the 'mudsplash' paradigm) (O'Regan, J. K., Rensink, R. A., & Clark, J. J. (1999). Nature 398, 34). By using a simplified mudsplash display, the present study investigated whether change blindness depends on (a). the timing of visual transients, and (b). the task that observers perform. Eight Gabor elements with random orientations were presented. One element (target) was rotated 45 degrees clockwise or counterclockwise without a temporal gap. High contrast visual transients, not overlapping with the elements, appeared at various times with respect to the target change. Observers reported where the change was (change localization), or in which direction the target rotated (change identification). Change localization was impaired primarily when the onset of the transient was at or after the change. In contrast, change identification was impaired mainly when the transient preceded the change. These results suggest that change localization and change identification are mediated in part by different mechanisms.

Adult↗
PubMed1998

Two dogmas of conceptual empiricism: implications for hybrid models of the structure of knowledge.

Concepts seem to consist of both an associative component based on tabulations of feature typicality and similarity judgments and an explanatory component based on rules and causal principles. However, there is much controversy about how each component functions in concept acquisition and use. Here we consider two assumptions, or dogmas, that embody this controversy and underlie much of the current cognitive science research on concepts. Dogma 1: Novel information is first processed via similarity judgments and only later is influenced by explanatory components. Dogma 2: Children initially have only a similarity-based component for learning concepts; the explanatory component develops on the foundation of this earlier component. We present both empirical and theoretical arguments that these dogmas are unfounded, particularly with respect to real world concepts; we contend that the dogmas arise from a particular species of empiricism that inhibits progress in the study of conceptual structure; and finally, we advocate the retention of a hybrid model of the structure of knowledge despite our rejection of these dogmas.

Association Learning↗