Implicit learning of a repeated segment in continuous tracking: a reappraisal

Several prior studies (e.g., Shea, Wulf, Whitacre, & Park, 2001; Wulf & Schmidt, 1997) have apparently demonstrated implicit learning of a repeated segment in continuous-tracking tasks. In two conceptual replications of these studies, we failed to reproduce the original findings. However, these findings were reproduced in a third experiment, in which we used the same repeated segment as that used in the Wulf et al. studies. Analyses of the velocity and the acceleration of the target suggests that this repeated segment could be easier to track than the random segments serving as control, accounting for the results of Wulf and collaborators. Overall these experiments suggest that learning a repeated segment in continuous-tracking tasks may be much more difficult than learning from a repeated sequence in conventional serial reaction time tasks. A possible explanation for this difference is outlined.     

Working memory and children's use of retrieval to solve addition problems

This study tested the hypothesis that children with high working memory capacities solve single-digit additions by direct retrieval of the answers from long-term memory more often than do children with low working memory capacities. Counting and reading letter span tasks were administered to groups of third-grade (mean age=107 months) and fourth-grade (mean age=118 months) children who were also asked to solve 40 single-digit additions. High working memory capacity was associated with more frequent use of retrieval and faster responses in solving additions. The effect of span on the use of retrieval increased with the size of the minimum addend. The relation between working memory measures and use and speed of retrieval did not depend on the numerical or verbal nature of the working memory task. Implications for developmental theories of cognitive arithmetic and theories of working memory are discussed.     

Chronometric evidence for memory retrieval in causal conditional reasoning: The case of the association strength effect

According to many models of conditional reasoning, correct responses to the uncertain forms affirmation of consequent (AC) and denial of antecedent (DA) rely on the retrieval of an alternative antecedent from semantic memory. The main prediction issuing from this hypothesis of online retrieval is that the associative strength of the relevant information in long-term memory affects the latency of its retrieval and then of the correct response of uncertainty to AC and DA. This prediction was tested in 64 adults who performed a syllogism evaluation task with familiar causal conditional premises. As predicted, correct responses of uncertainty to AC and DA were not only more frequent but also faster when the antecedent term was weakly rather than strongly associated with the consequent. In line with the semantic framework, we also observed that this strength effect in response times was reversed for incorrect responses of certainty to AC.     

Neural correlates of lexical and sublexical processes in reading

The purpose of the present study was to compare the brain regions and systems that subserve lexical and sublexical processes in reading. In order to do so, three types of tasks were used: (i). silent reading of very high frequency regular words (lexical task); (ii). silent reading of nonwords (sublexical task); and, (iii). silent reading of very low frequency regular words (sublexical task). All three conditions were contrasted with a visual/phonological baseline condition. The lexical condition engaged primarily an area at the border of the left angular and supramarginal gyri. Activation found in this region suggests that this area may be involved in mapping orthographic-to-phonological whole word representations. Both sublexical conditions elicited significantly greater activation in the left inferior prefrontal gyrus. This region is thought to be associated with sublexical processes in reading such as grapheme-to-phoneme conversion, phoneme assembly and underlying verbal working memory processes. Activation in the left IFG was also associated with left superior and middle temporal activation. These areas are thought to be functionally correlated with the left IFG and to contribute to a phonologically based form of reading. The results as a whole demonstrate that lexical and sublexical processes in reading activate different regions within a complex network of brain structures.     

From Environmental Factors to Outcomes: A Test of an Integrated Motivational Sequence

Research based on self-determination theory (SDT; E. L. Deci & R. M. Ryan, 1985, 2000) has shown that motivation is influenced by the social environment and also leads to outcomes. Based on such research, R. J. Vallerand (1997) has posited the existence at different levels of generality of an integrated motivational sequence where environmental factors (e.g., success/failure) influence perceptions of competence, autonomy, and relatedness (psychological mediators), which in turn determine to what extent one exhibits self-determined motivation. Motivation then leads to outcomes. The present study tested the validity of this integrated sequence at the situational level using an experimental design. Participants (N = 359) were randomly assigned to conditions of success or failure on a leisure task and elements of the integrated sequence were assessed. Structural equation modeling analyses provided support for the postulated motivational sequence. Results are discussed in light of SDT.This research was supported by grants and fellowships from the Fonds pour la formation de chercheurs et laide à la recherche (FCAR) and the Social Sciences Humanities Research Council of Canada (SSHRC) to Robert J. Vallerand. We would like to thank Sandrine Passelaigue for her help in collecting the data.     

Interplay between environmental and genetic factors in temperament/personality traits in horses (Equus caballus)

The aim of the present study was to broach the question of the relative influence of different genetic and environmental factors on different temperament/personality traits of horses (Equus caballus). The researchers submitted 702 horses to standardized experimental tests and investigated 9 factors, either genetic or environmental. Genetic factors, such as sire or breed, seemed to influence more neophobic reactions, whereas environmental factors, such as the type of work, seemed to play a more dominant role in reactions to social separation or learning abilities. Additive effects were evident, showing how environmental factors may modulate behavioral traits. This study constitutes a first step toward understanding the relative weights of genetic factors and how the environment may intervene in determining individual behavioral characteristics.     

Cytokine stress responses depend on lateralization in mice

In mice, lateralization as assessed by paw preference represents a behavioral trait linked to immune reactivity and stress susceptibility. Right-pawed mice are more reactive to stress than left-pawed animals when brain metabolism, activation of the corticoid axis, and depression of lymphoproliferation are studied. Since stress responses include cytokine production, we address the possibility that lateralization influences the production of cytokines--especially interleukin (IL)-1--responsible for depression of lymphoproliferation and activation of the corticoid axis. Increased plasma IL-1 level that may be considered as a stress marker, was observed in right- but not in left-pawed mice submitted to a 4 h-restraint. Likewise, plasma levels were greater in right- than in left-pawed animals 2 h after the administration of a low dose of lipopolysaccharides (LPS). By contrast, there was no lateralization effect in restraint-induced plasma level of IL-6 or in the LPS-induced increase in plasma IL-10. Prazosin, an alpha1/alpha2 adrenoreceptor antagonist, drastically increased plasma IL-10 induced by LPS, reduced plasma levels of IL-1 and abolished the effect of lateralization observed after LPS alone. This suggests that alpha-adrenergic modulation of IL-1 production depends on lateralization through mechanisms that need further investigation.     

Absence of perceptual processing during reconfiguration of task set

The authors manipulated stimulus contrast and response-stimulus interval in the alternating runs paradigm to investigate whether early processing could be carried out during a task switch. Subjects alternated between judging the magnitude and the parity of a digit. The results suggested that early processing was not carried out during the task switch (Experiment 1), even in the absence of potentially confounding auditory or visual warning signals (Experiment 2). This processing was, however, carried out in parallel with a demanding operation in a 2nd task (Experiment 3), using the display parameters of Experiments 1 and 2 in the psychological refractory period paradigm. It is concluded that, functionally, task switching may impose a hard bottleneck even for very early stimulus processing. ((c) 2003 APA, all rights reserved)     

Processing of metaphoric and non-metaphoric alternative meanings of words after right- and left-hemispheric lesion

This study examines the specificity of the contribution of the right hemisphere to the processing of metaphoric meaning of words. Ten right- and 10 left-hemisphere-damaged subjects, and 20 normal control subjects were submitted to: (1) a word-triad task where they had to associate alternative metaphoric and non-metaphoric words to a target word, and to (2) a word-dyad task where they had to decide whether or not there was a semantic relationship between two words. The two tasks aimed at differentiating between the subjects' preference for a given semantic meaning versus a genuine semantic deficit for a particular meaning. Results revealed that both right- and left-hemisphere-damaged groups presented a genuine semantic deficit for the processing of metaphoric meaning. The absence of a double dissociation between the two brain-damaged groups does not support the hypothesis of a specific contribution of the right-hemisphere to the processing of metaphoric meaning of words.