The formation of structurally relevant units in artificial grammar learning

A total of 78 adult participants were asked to read a sample of strings generated by a finite state grammar and, immediately after reading each string, to mark the natural segmentation positions with a slash bar. They repeated the same task after a phase of familiarization with the material, which consisted, depending on the group involved, of learning items by rote, performing a shortterm matching task, or searching for the rules of the grammar. Participants formed the same number of cognitive units before and after the training phase, thus indicating that they did not tend to form increasingly large units. However, the number of different units reliably decreased, whatever the task that participants had performed during familiarization. This result indicates that segmentation was increasingly consistent with the structure of the grammar. A theoretical account of this phenomenon, based on ubiquitous principles of associative memory and learning, is proposed. This account is supported by the ability of a computer model implementing those principles, PARSER, to reproduce the observed pattern of results. The implications of this study for developmental theories aimed at accounting for how children become able to parse sensory input into physically and linguistically relevant units are discussed.     

Situational consistency in behavioral patterns of aggressive boys: Methodological considerations on observational measures

The issue of situational consistency is of great interest for early intervention with aggressive boys, but efforts to show behavior stability across settings have been unsuccessful to date, due principally to methodological problems. It is argued here that a more appropriate matching of response form, interaction partner, and situations should increase the situation consistency of observed behavior. The results support this proposition in that, more crosssetting behavior consistency was found in the pairing of situations where aggressive boys (age 6–7 years) were interacting with an adult female (mother/child versus baby-sitter/child) than in the pairing of situations where the boys were interacting with an adult male (mother/child versus father/child) or with the teacher in a nondyadic situation (classroom). The implications of using an extreme group are also discussed.This research program was funded by Le Conseil Québécois de la Recherche Sociale, the Quebec Government's FCAR research program, the Social Sciences and Humanities Research Council of Canada, the Canadian Ministry of Employment and Immigration, and the University of Montreal FDR program.     

Antialiasing: A technique for smoothing jagged lines on a computer graphics image—an implementation on the Amiga

Images displayed on computer graphics displays often suffer from the presence of aliasing artifacts that give a jagged appearance to lines or polygon edges displayed on the screen. This paper details the problems associated with these artifacts and presents a method for drawingantialiased lines—ones in which the artifacts have been considerably reduced. The line-drawing routine is further developed to incorporategamma correction, to take into account the nonlinear relationship between the intensity of the light emission from the phosphor of the monitor and the grayscale values used to control the intensity on the screen.     

Attentional cues in chronic schizophrenia: abnormal disengagement of attention.

Posner's (1980) reaction time (RT) paradigm was used to examine the engagement and disengagement operations of visual selective attention in patients with schizophrenia. In the 1st experiment, 14 medicated, chronic schizophrenic subjects (diagnosed by criteria of the Diagnostic and Statistical Manual of Mental Disorders; American Psychiatric Association, 1987) and 15 age-matched normal control subjects made a speeded response to a target preceded by a valid, an invalid, or no cue. Control subjects showed the expected advantage and disadvantage in RT for valid and invalid cues, which suggests intact engagement and disengagement operations. For schizophrenic patients, valid cues also enhanced RT, but invalid cues did not slow RT. Similar results were found in the 2nd experiment. The failure of unpredictable, invalid cues to inhibit RT in chronic schizophrenia may be related to an abnormality in the disengagement operation of selective attention.     

Effet de l'intensité sur la catégorisation des prototypes émotionnels faciaux chez l'enfant et l'adulte

This study examines whether the intensity of facial emotional prototypes influences the process of their categorization in children and young adults. Two facial prototypes, one of happiness and one of disgust, including action units of three different intensities, were shown to 30 children and 30 adults who were submitted to a categorization task. As predicted, categorization accuracy was found to increase, in general, as a function of the intensity of action units. Adults were better than children but only for the categorization of disgust when the action unit intensity was weak. The happiness prototype was better categorized than the disgust prototype, and two types of errors were clearly more frequent than the others in the categorization of the disgust prototype: disgust/anger and disgust/sadness. The results are discussed in relation to the regulative processes involved in the socialization of emotion.     

The spatial frame of reference in object naming and discrimination of left-right reflections

The effects of stimulus rotation and observer's head-tilt position on various pattern-recognition tasks were investigated to compare the external directions most closely aligned with the spatial frame of reference. Specifically, the effects of these factors on the time to name objects were compared with their effects on the time to discriminate left-facing from right-facing lateral views of these objects, as well as with their effects on the time to discriminate normal from mirror-imaged alphanumeric characters. The naming task relied upon a reference frame more closely aligned with retinal directions than with environmental directions. In contrast, both discrimination tasks relied upon a frame aligned more closely with environmental directions. Overall, the nature of the task exerts a greater influence on the directions with which the frame of reference is aligned than do the stimulus attributes.     

COMPETENCES A COMMUNIQUER ET RELATIONS PRIVILEGIEES ENTRE ENFANTS: COMPARAISON ENTRE DEUX GROUPES D'AGE*

The purpose of this study is to analyse the specificity of interactions between preschool friends, whose relationships are built on a voluntary and stable choice of a particular partner. The sample consisted of 18 unisexual triads of children aged 3 to 4 years (9 male and 9 female) from 5 Parisian kindergarten. These triads were compared with 18 others, composed of children aged 4 to 5 years (9 male and 9 female), from a previous study (Werebe et Boudonnière, in press). Each triad was composed of a dyad of friends plus a third familiar partner, all three classmates. The dyads of friends were selected on the basis of the following criteria: (1) a reciprocal and preferential search for one another; (2) a voluntary choice of the friend, without intervention from parents or teachers. The children were videotaped without their knowledge, without adult presence, in a familiar room of their school. The experimental setting was standardized in each of the 5 schools. The experimental paradigm was a variant of the one created by Nadel and Baudonnière (1980, 1982), with an important modification: the ten categories of matching objects were provided in double sets for the three children. Four indices were used for the data analysis: holding and appropriation of objects; offering of objects; competition to hold objects and verbalizations. The findings confirmed the principal hypothesis: that interactions between friends differ from those with the third partner, in both age groups, quantitatively (density of interactions) and qualitatively (reciprocal offerings and verbal communications). Furthermore, the findings revealed that the younger children had more difficulty than the older ones, to manage the triadic situation, especially in this situation with the constraint imposed by the presence of two sets of matching objects for three partners.     

A size-congruency effect in memory for visual shape

In five experiments, visual shapes were shown at either a small or a large size for study in the learning phase of a recognition memory experiment. Later, in the test phase, recognition memory was tested in anold-new paradigm in which an equal number of new shapes were mixed at random with previously seen shapes. Half of theold shapes were shown at the same size as in the learning phase, whereas half were shown at the other size. In every experiment, shapes tested at the same size as shown in the learning phase were recognized more quickly and more accurately than shapes tested at a different size. This size-congruency effect was found for line drawings of natural objects and for unfamiliar shapes (i.e., blobs and stick figures). Furthermore, the magnitude of the size-congruency effect depended on the degree of discrepancy between the learning size and the test size. Together, the results suggest that visual shape memory can be sensitive to the size at which patterns are originally encoded, and that the speed and accuracy of recognition memory is influenced by the size of a shape.