Three-dimensional spatial representation in freely swimming fish

Research on spatial cognition has focused on how animals encode the horizontal component of space. However, most animals travel vertically within their environments, particularly those that fly or swim. Pelagic fish move with six degrees of freedom and must integrate these components to navigate accurately--how do they do this? Using an assay based on associative learning of the vertical and horizontal components of space within a rotating Y-maze, we found that fish (Astyanax fasciatus) learned and remembered information from both horizontal and vertical axes when they were presented either separately or as an integrated three-dimensional unit. When information from the two components conflicted, the fish used the previously learned vertical information in preference to the horizontal. This not only demonstrates that the horizontal and vertical components are stored separately in the fishes' representation of space (simplifying the problem of 3D navigation), but also suggests that the vertical axis contains particularly salient spatial cues--presumably including hydrostatic pressure. To explore this latter possibility, we developed a physical theoretical model that shows how fish could determine their absolute depth using pressure. We next considered full volumetric spatial cognition. Astyanax were trained to swim towards a reward in a Y-maze that could be rotated, before the arms were removed during probe trials. The subjects were tracked in three dimensions as they swam freely through the surrounding cubic tank. The results revealed that fish are able to accurately encode metric information in a volume, and that the error accrued in the horizontal and vertical axes whilst swimming in probe trials was similar. Together, these experiments demonstrate that unlike in surface-bound rats, the vertical component of the representation of space is vitally important to fishes. We hypothesise that the representation of space in the brain of vertebrates could ultimately be shaped by the number of the degrees of freedom of movement that binds the navigating animal.     

Negative internal causal attributions of a specific offense and forgiveness

Causal attributions are important social‐cognitive predictors of forgiveness. This article presents the Transgression Attribution Questionnaire (TAQ), a measure of one's negative internal causal attributions of a specific offense. In 4 studies, scores on the TAQ showed initial evidence of estimated internal consistency, temporal stability, and construct validity. Negative internal attributions for the cause of a transgression predicted lower levels of empathy and forgiveness. Furthermore, scores on the TAQ predicted forgiveness over and above the hurtfulness of the offense, relationship commitment, and a general measure of internal causal attributions in relationships. The current research bridges research on internal causal attributions and forgiveness. Implications for the social‐cognitive study of forgiveness and the measurement of causal attributions are discussed.     

Three-dimensional spatial representation in freely swimming fish

Research on spatial cognition has focused on how animals encode the horizontal component of space. However, most animals travel vertically within their environments, particularly those that fly or swim. Pelagic fish move with six degrees of freedom and must integrate these components to navigate accurately—how do they do this? Using an assay based on associative learning of the vertical and horizontal components of space within a rotating Y-maze, we found that fish (Astyanax fasciatus) learned and remembered information from both horizontal and vertical axes when they were presented either separately or as an integrated three-dimensional unit. When information from the two components conflicted, the fish used the previously learned vertical information in preference to the horizontal. This not only demonstrates that the horizontal and vertical components are stored separately in the fishes’ representation of space (simplifying the problem of 3D navigation), but also suggests that the vertical axis contains particularly salient spatial cues—presumably including hydrostatic pressure. To explore this latter possibility, we developed a physical theoretical model that shows how fish could determine their absolute depth using pressure. We next considered full volumetric spatial cognition. Astyanax were trained to swim towards a reward in a Y-maze that could be rotated, before the arms were removed during probe trials. The subjects were tracked in three dimensions as they swam freely through the surrounding cubic tank. The results revealed that fish are able to accurately encode metric information in a volume, and that the error accrued in the horizontal and vertical axes whilst swimming in probe trials was similar. Together, these experiments demonstrate that unlike in surface-bound rats, the vertical component of the representation of space is vitally important to fishes. We hypothesise that the representation of space in the brain of vertebrates could ultimately be shaped by the number of the degrees of freedom of movement that binds the navigating animal.     

A comparison of methods for measuring the interletter similarity between capital letters

Measures of interletter similarity are often required in perception experiments. The most reliable and valid of the available measures appears to be Townsend’s (1971) set of similarity parameters based on the Luce choice model. A simple mechanical measure offered a fairly strong prediction of the Luce choice-model similarity measure, as did a subjective rating measure based on the 10-point visual similarity ratings of eight subjects. By comparison, Gibson et al.’s (1963) matching-confusion matrix faired poorly, as did Gibson’s (1969) distinctive feature analysis based on a letter pair’s number of shared features. Distinctive feature analysis was significantly improved by substituting the feature set proposed by Geyer and DeWald (1973) or by weighting the features optimally via regression analysis. Such analyses suggested that figural curvature may be a particularly important perceptual feature, but in no case did these feature-analytic models predict the Luce measure as well as the mechanical or subjective rating measures.     

Stability of teacher temperament ratings over 6 and 12 months

Six and 12-month stability of teacher ratings of temperament was studied in four samples. For the two samples retested after a 6-month interval, the same teacher provided the original and retest ratings. For the two samples retested after a 12-month interval, different teachers provided the retest ratings than provided the original ratings. Four indices of stability were investigated for each sample: (a) cross-rank stability, (b) within-person stability (c) absolute score stability, and (d) factorial stability. Factorial stability was demonstrated for all samples. For the other three indices of stability, 6-month stability was moderate to high, and significantly higher than the 12-month stability. The general pattern of results is comparable to temperament rating data from parents, with specific coefficients being somewhat higher.