Investigation into Combinatory Systems with Dual Combinators

Combinatory logic is known to be related to substructural logics. Algebraic considerations of the latter, in particular, algebraic considerations of two distinct implications (, ), led to the introduction of dual combinators in Dunn & Meyer 1997. Dual combinators are "mirror images" of the usual combinators and as such do not constitute an interesting subject of investigation by themselves. However, when combined with the usual combinators (e.g., in order to recover associativity in a sequent calculus), the whole system exhibits new features. A dual combinatory system with weak equality typically lacks the Church-Rosser property, and in general it is inconsistent. In many subsystems terms "unexpectedly" turn out to be weakly equivalent. The paper is a preliminary attempt to investigate some of these issues, as well as, briefly compare function application in symmetric -calculus (cf. Barbanera & Berardi 1996) and dual combinatory logic.     

Attention and joint attention in preschool children with autism

Three experiments examined the role of attention in explaining dyadic (child-adult) and triadic (child-adult-object) joint attention difficulties in autism. Experiments 1 and 2 investigated children's ability to orient to an adult's attention bid and to follow the direction of a human or nonhuman cue. Experiment 3 tested ability to disengage and shift attention to objects. Results showed autism-specific difficulties at both dyadic and triadic levels. Children with autism were less responsive than developmentally delayed controls in orienting to attention bids and in following a human head-turn cue yet had no difficulty in shifting attention and were faster overall in orienting to targets. Results suggest a specific developmental delay in which children with autism rely on the presence of objects in the visual field to guide action. The relation between this problem and autistic children's difficulties with human communicative signals is discussed.     

Analityczne komponenty definicji arbitralnych

Tre: Wstp. I. Definicje arbitralne. II. Syntetyczne konsekwencje definicji arbitralnych III. Analityczne i rzeczowe komponenty definicji arbitralnych. IV. Zdania analityczne.Artyku ten w nieznacznym tylko stopniu róni si od pracy doktorskiej, któr przedstawiem w 1962 r. Jak najuprzejmiej dzikuj Prof. Dr M. Kokoszyskiej-Lutman, Prof. Dr J. Supeckiemu oraz Doc. Dr M. Przeckiemu za szereg uwag i wskazówek, z których tak wiele skorzystaem przygotowujc ostateczn redakcj pracy.     

Recenzje

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Reviews

     

Effects of reinforcement history on response rate and response pattern in periodic reinforcement

Several researchers have suggested that conditioning history may have long-term effects on fixed-interval performances of rats. To test this idea and to identify possible factors involved in temporal control development, groups of rats initially were exposed to different reinforcement schedules: continuous, fixed-time, and random-interval. Afterwards, half of the rats in each group were studied on a fixed-interval 30-s schedule of reinforcement and the other half on a fixed-interval 90-s schedule of reinforcement. No evidence of long-term effects attributable to conditioning history on either response output or response patterning was found; history effects were transitory. Different tendencies in trajectory across sessions were observed for measures of early and late responding within the interreinforcer interval, suggesting that temporal control is the result of two separate processes: one involved in response output and the other in time allocation of responding and not responding.     

The frequency effect for pseudowords in the lexical decision task

Four experiments were designed to investigate whether the frequency of words used to create pseudowords plays an important role in lexical decision. Computational models of the lexical decision task (e.g., the dual route cascaded model and the multiple read-out model) predict that latencies to low-frequency pseudowords should be faster than latencies to high-frequency pseudowords. Consistent with this prediction, results showed that when the pseudowords were created by replacing one internal letter of the base word (Experiments 1 and 3), high-frequency pseudowords yielded slower latencies than low-frequency pseudowords. However, this effect occurred only in the leading edge of the response time (RT) distributions. When the pseudowords were created by transposing two adjacent internal letters (Experiment 2), high-frequency pseudowords produced slower latencies in the leading edge and in the bulk of the RT distributions. These results suggest that transposed-letter pseudowords may be more similar to their base words than replacement-letter pseudowords. Finally, when participants performed a go/no-go lexical decision task with one-letter different pseudowords (Experiment 4), high-frequency pseudowords yielded substantially faster latencies than low-frequency pseudowords, which suggests that the lexical entries of high-frequency words can be verified earlier than the lexical entries of low-frequency words. The implications of these results for models of word recognition and lexical decision are discussed.     

Statistical computations over a speech stream in a rodent

Statistical learning is one of the key mechanisms available to human infants and adults when they face the problems of segmenting a speech stream (Saffran, Aslin, & Newport, 1996) and extracting long-distance regularities (G6mez, 2002; Pe?a, Bonatti, Nespor, & Mehler, 2002). In the present study, we explore statistical learning abilities in rats in the context of speech segmentation experiments. In a series of five experiments, we address whether rats can compute the necessary statistics to be able to segment synthesized speech streams and detect regularities associated with grammatical structures. Our results demonstrate that rats can segment the streams using the frequency of co-occurrence (not transitional probabilities, as human infants do) among items, showing that some basic statistical learning mechanism generalizes over nonprimate species. Nevertheless, rats did not differentiate among test items when the stream was organized over more complex regularities that involved nonadjacent elements and abstract grammar-like rules.     

Confirmatory factor analysis of parents' and teachers' ratings of DSM-IV symptoms of attention deficit hyperactivity disorder in a Spanish sample

Confirmatory factor analysis examined the factor structure of DSM IV Attention Deficit Hyperactivity Disorder symptoms and analyzed the differences in informants' ratings of ADHD symptoms by children's age and sex. A sample of 1,018 Spanish school children, 574 girls and 444 boys, ages 4 to 12 years, was rated by teachers and parents. Confirmatory factor analysis showed a similar fit for the three-factor model of Inattention, Hyperactivity, and Impulsivity (teachers: CFI = .976, RMR = .041, % of total variance = 83.2; parents: CFI = .969, RMR = .037, % of total variance = 82.7) and for the two-factor model of Inattention and Hyperactivity Impulsivity (teachers: CFI = .958, RMR = .044, % of total variance = 79.3; parents: CFI = .961, RMR = .038, % of total variance, 79.9). The two-factor model was selected as a parsi monious representation of the teachers' and parents' ratings of ADHD symptoms. Analyses of variance indicated significant differences in teachers' and parents' mean ratings across sex and school grades of children.     

Death anxiety and death depression in Spanish nurses

This study examined the dimensional structure of Tomás-Sábado and Gómez-Benito's Death Anxiety Inventory and Templer, et al.'s Death Depression Scale-Revised. The responses of 244 Spanish nurses to the Spanish forms of both scales were evaluated by means of a principal axis factor analysis with direct Oblimin rotation. Five significant factors were identified: Internally Generated Death Anxiety, Death Depression, Externally Generated Death Anxiety, Death Threat, and Death Sadness, accounting for 51.6% of the variance. The distribution of the factor loadings for the items of both scales on the five factors supported the discriminant validity of the constructs specific to each of the scales and justified their use in evaluating death anxiety and death depression independently.