Contribution of the priming paradigm to the understanding of the conceptual developmental shift from 5 to 9 years of age

We conducted three experiments to study the role of instrumental (e.g. knife–bread) and categorical (e.g. cake–bread) relations in the development of conceptual organization with a priming paradigm, by varying the nature of the task (naming – Experiment 1 – or categorical decision – Experiments 2 and 3). The participants were 5‐, 7‐ and 9‐year‐old children and adults. The results showed that on both types of task, adults and 9‐year‐old children presented instrumental and categorical priming effects, whereas 5‐year‐old children presented mainly instrumental priming effects, with categorical effects remaining marginal. Moreover, the magnitude of the instrumental priming effects decreased with age. Finally, the priming effects observed for 7‐year‐old children depended on the task, especially for the categorical effects. The theoretical implications of these results for our understanding of conceptual reorganization from 5 to 9 years of age are discussed.     

Children's and adolescents' perception of the authenticity of smiles

Recently, Thibault and colleagues described the Duchenne marker as a cultural dialect for the perception of smile authenticity. The current study had the goal to follow up on this finding and to investigate the cues that French Canadian children use to evaluate the authenticity of smiles from members of three ethnic groups. The authenticity of six smiles differing in intensity and presence of orbicularis oculi (Duchenne marker) was rated by 1206 children from 4 to 17 years of age. No differences were found as a function of encoder group. All children perceived medium Duchenne smiles as more authentic than equally intense medium non-Duchenne smiles. Furthermore, results suggest a decrease in the reliance on intensity across the age span. Younger children use the intensity marker along the whole continuum to infer authenticity. In contrast, older children (14- to 17-year-olds) rated all smiles that did not contain the Duchenne marker as roughly equally low in authenticity.     

Attentional and anatomical considerations for the representation of simple stimuli in visual short-term memory: evidence from human electrophysiology

Observers encoded the spatial arrangement of two or three horizontal line segments relative to a square frame presented for 150 ms either in left or right visual field and either above or below the horizontal midline. The target pattern was selected on the basis of colour (red vs. green) from an equivalent distractor pattern in the opposite left–right visual hemifield. After a retention interval of 450 or 650 ms a test pattern was presented at fixation. The task was to decide whether the test was the same as the encoded pattern or different. Selection of the to-be-memorised pattern produced an N2pc response that was not influenced by the number of line segments nor by the length of the retention interval, but that was smaller in amplitude for patterns presented in the upper visual field compared with patterns presented in the lower visual field. A sustained posterior contralateral negativity (SPCN) followed the N2pc. The SPCN was larger for patterns with three line segments than for two, was larger for patterns encoded from lower visual field than from upper visual field, and returned to baseline sooner for the shorter retention interval than for the longer interval. These results, and others, provide an interesting and complex pattern of similarities and differences between the N2pc and SPCN, consistent with the view that N2pc reflects mechanisms of attentional selection whereas the SPCN reflects maintenance in visual short-term memory.     

Attentional and structural constraints on visual encoding

We examined the mechanisms that mediate the transfer of information from visual input to storage in memory. Observers performed two concurrent tasks, one of which required input into memory. We discovered that the processes involved in the transfer of information from sensory input into memory cause slowing in concurrent cognitive tasks (dual-task slowing). We used the dual-task slowing effect to demonstrate that memory encoding requires more time when more information is to be encoded and to show that dual-task slowing occurs long after the initial perceptual encoding of visual information (Exp. 1). These results suggest a late and central locus of interaction between the two tasks. Experiment 2 also used two concurrent tasks. However, we reversed the direction of interaction between them and produced a memory deficit from the execution of a concurrent task. Together the results suggest that the mechanisms that encode information into memory belong to a family of mechanisms that are involved in dual-task slowing phenomena and that have been studied under the rubric of the PRP effect (psychological refractory period). We were able to locate the most probable locus of the dual-task interactions to a process that appears necessary for memory encoding. We call this process short-term consolidation. Received: 20 July 1997 / Accepted: 17 March 1998     

An exploration of genetic g: Hierarchical factor analysis of cognitive data from the western reserve twin project

Hierarchical factor analyses involving Schmid-Leiman transformations (Schmid & Leiman, 1957) were conducted on specific cognitive abilities data collected in a sample of 148 identical (MZ) and 135 same-sex fraternal (DZ) twin pairs. Two main questions were addressed: First, are genetic influences on specific cognitive abilities simply a reflection of their g loading, or are different sets of genes affecting separate abilities? Second, to the extent that specific cognitive abilities are affected by common genetic variance, how similar is the common genetic factor to a phenotypic factor reflecting g? Model fitting results suggest that genetic influences on specific abilities are a reflection of both general intelligence and genetic influences specific to separate abilities and that loadings on the common genetic factor are more highly correlated with phenotypic g loadings than are common environmental factor loadings.