Sara Cordes

Ordinal understanding is involved in understanding social hierarchies, series of actions, and everyday events. Moreover, an appreciation of numerical order is critical to understanding number at a highly abstract, conceptual level. In this paper, we review findings concerning the development and expression of ordinal numerical knowledge in preverbal human infants in light of literature about the same cognitive abilities in non-human animals. We attempt to reconcile seemingly contradictory evidence, provide new directions for prospective research, and evaluate the shared basis of ordinal knowledge among non-verbal organisms. Our review of the research leads us to conclude that both infants and non-human animals are adapted to respond to monotonic progressions in numerical order, consonant with mathematical definitions of numerical order. Further, we suggest that patterns in the way that infants and non-human animals process numerical order can be accounted for by changes across development, the conditions under which representations are generated, or both.

An emerging corpus of clinical and neuroimaging data suggests that subsecond and suprasecond durations are represented via 2 distinct mechanisms in humans; however, surprisingly, behavioral data to this effect are lacking. In our first experiment, we perform the first systematic exploration of subsecond and suprasecond timing within the same session in nonhuman subjects. Rats were trained to judge the relative duration of 2 sequential stimuli, responding on one lever if the first stimulus was longer or on a second lever if the converse was true. Our data provide strong evidence of an abstract understanding of longer and shorter for durations in the suprasecond range, whereas responding was at chance levels for durations in the subsecond range. Data from a second experiment reveal that this pattern is not due to an inability to time subsecond signals, as rats respond systematically in subsecond and suprasecond bisection tasks. Together, our results provide the first clear behavioral evidence of a discontinuity in the mental time line. These data from rats are discussed in light of similar findings of a discontinuity in the mental number line in human infants.

Although young infants have repeatedly demonstrated successful numerosity discrimination across large sets when the number of items in the sets changes twofold (E. M. Brannon, S. Abbott, & D. J. Lutz, 2004; J. N. Wood & E. S. Spelke, 2005; F. Xu & E. S. Spelke, 2000), they consistently fail to discriminate a twofold change in number when one set is large and the other is small (<4 items; F. Feigenson, S. Carey, & M. Hauser, 2002; F. Xu, 2003). It has been theorized that this failure reflects an incompatibility in representational systems for small and large sets. The authors investigated the ability of 7-month-old infants to compare small and large sets over a variety of conditions. Results reveal that infants can successfully discriminate small from large sets when given a fourfold change, but not a twofold change, in number. The implications of these results are discussed in light of current theories of number representation.

ABSTRACT Studies have shown a higher than average incidence of mental illness in adult artists. We asked whether an association between symptoms of affective disorders and the arts is found as early as adolescence, using a sample of 2,482 15- to 16-year-old adolescents. Teens involved in afterschool arts had higher depressive symptom scores than those not involved, and the association between arts involvement and depressive symptoms held only for those scoring above the median in working memory test scores. We consider reasons for these findings, including the possibility that shared cognitive vulnerabilities may underlie both the depressive symptoms and increased arts practice, and that cognitive resources (working memory) facilitate the adaptive use of these vulnerabilities. (PsycINFO Database Record (c) 2013 APA, all rights reserved)