Transfer to intermediate forms following concept discrimination by pigeons: chimeras and morphs

Two experiments examined pigeons' generalization to intermediate forms following training of concept discriminations. In Experiment 1, the training stimuli were sets of images of dogs and cats, and the transfer stimuli were head/body chimeras, which humans tend to categorize more readily in terms of the head part rather than the body part. In Experiment 2, the training stimuli were sets of images of heads of dogs and cats, and the intermediate stimuli were computer-generated morphs. In both experiments, pigeons learned the concept discrimination quickly and generalized with some decrement to novel instances of the categories. In both experiments, transfer tests were carried out with intermediate forms generated from both familiar and novel exemplars of the training sets. In Experiment 1, the pigeons' transfer performance, unlike that of human infants exposed to similar stimuli, was best predicted by the body part of the stimulus when the chimeras were formed from familiar exemplars. Spatial frequency analysis of the stimuli showed that the body parts were richer in high spatial frequencies than the head parts, so these data are consistent with the hypothesis that categorization is more dependent on local stimulus features in pigeons than in humans. There was no corresponding trend when the chimeras were formed from novel exemplars. In Experiment 2, when morphs of training stimuli were used, response rates declined smoothly as the proportion of the morph contributed by the positive stimulus fell, although results with morphs of novel stimuli were again less orderly.     

Finite basis problems and results for quasivarieties

Let be a finite collection of finite algebras of finite signature such that SP( ) has meet semi-distributive congruence lattices. We prove that there exists a finite collection ₁ of finite algebras of the same signature, , such that SP( ₁) is finitely axiomatizable.We show also that if , then SP( ₁) is finitely axiomatizable. We offer new proofs of two important finite basis theorems of D. Pigozzi and R. Willard. Our actual results are somewhat more general than this abstract indicates.While working on this paper, the first author was partially supported by the Hungarian National Foundation for Scientific Research (OTKA) grant no. T37877 and the second author was supported by the US National Science Foundation grant no. DMS-0245622.Special issue of Studia Logica: Algebraic Theory of Quasivarieties Presented by M. E. Adams, K. V. Adaricheva, W. Dziobiak, and A. V. Kravchenko     

The influence of intentional and incidental learning on acquiring spatial knowledge during navigation

In order to study the influence of intentional and incidental learning conditions on route learning, young adults walked a route through a university building. Half of the participants focused their attention on the route (intentional learning condition), while the other half did not (incidental learning condition). Five tests of spatial knowledge were employed: a route-length-estimation, landmark recognition, landmark ordering, map-drawing and navigation task. The intentional group performed better than the incidental group on the map-drawing and navigation task. No difference between the intentional and incidental group was found on the landmark-recognition and landmark-ordering task. Moreover, the intentional group overestimated the walking distance, while the incidental group underestimated it. These results suggest that route knowledge (landmark recognition and landmark ordering) requires less effortful processing than survey knowledge (developing a map-like representation and actual navigation).     

Learning in context: linguistic and attentional constraints on children's color term learning

Three experiments investigated whether linguistic and/or attentional constraints might account for preschoolers' difficulties when learning color terms. Task structure and demands were equated across experiments, and both speed and degree of learning were compared. In Experiment 1, 3-year-olds who were matched on vocabulary score were taught new secondary color terms by corrective, semantic, or referential linguistic contrast. Corrective contrast produced more rapid and more extensive learning than did either semantic or referential contrast, supporting the hypothesis that targeted linguistic feedback facilitates learning. Experiment 2 replicated and extended the first experiment with Italian children and found cross-cultural differences in the amount learned about colors named differently in the two languages. In Experiment 3, some of the children were introduced to the new terms within a context of enhanced perceptual salience. These children learned as fast and performed as accurately as those given corrective linguistic feedback in Experiment 1.     

Shared processes in spatial rotation and musical permutation

An experiment was conducted in which subjects performed a three-dimensional spatial rotation test (24 trials) and a new test involving judgments of musical permutations (64 trials). Two types of musical permutations were used, including retrograde and inverse. In a retrograde permutation, the criterion melody was played backward in the test melody, and in an inverse permutation, an ascending or descending interval in the criterion melody became an opposite in the test melody. Subjects included 32 male and 64 female undergraduates at the University of Toronto. Regression analysis clearly showed that it was easiest to compare short retrograde permutations and that accuracy at discerning retrograde permutations predicted accuracy at judging spatial rotations. The implication is that a higher order ability to discriminate contour underlies both kinds of judgments.     

Partner Orientation and Speaker's Knowledge as Conflicting Parameters in Language Production

Two parameters of language production, the partner model and the mentally represented knowledge about a spatial constellation, are investigated with respect to their influence on spatial reference. At issue is whether the verbally expressed point of view in route directions is primarily influenced by the needs of the partner or by the underlying mental representation of the speaker stemming from his or her own experience with an object. Two experiments in which participants (N = 90) were asked to produce a set of route directions are reported. The experimental situation was such that the point of view of the speaker did not correspond to the point of view of the partner. The results show that more participants localize from their own point of view than from the point of view of the partner. Discussion centers on the fact that speakers do not always behave in a truly partner-oriented manner.     

A Complete Axiom System for Polygonal Mereotopology of the Real Plane

This paper presents a calculus for mereotopological reasoning in which two-dimensional spatial regions are treated as primitive entities. A first order predicate language with a distinguished unary predicate c(x), function-symbols , · and – and constants 0 and 1 is defined. An interpretation for is provided in which polygonal open subsets of the real plane serve as elements of the domain. Under this interpretation the predicate c(x) is read as region x is connected and the function-symbols and constants are given their meaning in terms of a Boolean algebra of polygons. We give an alternative interpretation based on the real closed plane which turns out to be isomorphic to A set of axioms and a rule of inference are introduced. We prove the soundness and completeness of the calculus with respect to the given interpretation.     

Cross‐sectional study on the relationship between music training and working memory in adults

Learning to play musical instruments has been shown to enhance a wide variety of cognitive domains. The present study investigated the specific aspects of working memory (WM) that differed between adult musicians and non‐musicians. Twenty‐four musicians and 30 non‐musicians matched for age, gender, years of formal education, and verbal intelligence performed several WM tasks. A multivariate analysis of covariance, wherein family income was controlled, revealed that musicians outperformed non‐musicians in tasks related to visual–motor coordination, visual scanning ability, visual processing speed, and spatial memory. However, no significant differences were found in phonological and visual memory capacity. This study supports the view that music training is associated to specific (and not general) WM skills.     

You never know where you are going until you know where you have been: Disorganized search after stroke

Disorders in spatial exploration can be expressed in a disorganized fashion of target cancellation. There is debate regarding whether disorganized search is related to stroke in general, to right brain damage or to unilateral spatial neglect (USN) in particular. In this study, 280 stroke patients and 37 healthy control subjects performed a computerized shape cancellation test. We investigated the number of perseverations and several outcome measures regarding disorganized search: Consistency of search direction (best r), distance between consecutive cancelled targets and intersections with paths between previous cancelled targets. We compared performance between patients with left and right brain damage (L, R) and with and without USN (USN+, USN?), resulting in four subgroups: LUSN?, RUSN?, LUSN+, and RUSN+. Higher numbers of intersections were found for the left brain‐ and right brain‐damaged patients with USN and for the right brain‐damaged patients without USN, compared to healthy control subjects. Furthermore, right brain‐damaged patients with USN showed a higher number of intersections compared to right brain‐damaged patients without USN and compared to left brain‐damaged patients with USN. To conclude, disorganized search was most strongly related to the neglect syndrome, and patients with more severe USN were even more impaired.