Creating semantics in tool use

This article presents the first evidence for a functional link between tool use and the processing of abstract symbols like Arabic numbers. Participants were required to perform a tool-use task after the processing of an Arabic number. These numbers represented either a small (2 or 3) or a large magnitude (8 or 9). The tool-use task consisted in using inverse pliers for gripping either a small or a large object. The inverse pliers enable to dissociate the hand action from the tool action in relation to the object (i.e., closing the hand led to an opening of the tool and vice versa). The number/tool hypothesis predicts that the quantity representation associated with Arabic numbers will interact with the action of the tool toward the object. Conversely, the number/hand hypothesis predicts that the quantity associated with numbers will interact with the action of the hand toward the tool. Results confirmed the first hypothesis and rejected the second. Indeed, large numbers interacted with the action of the tool, such that participants were longer to perform an “opening-hand/closing-tool” action after the processing of large numbers. Moreover, no effect was detected for small numbers, confirming previous studies which used only finger movements. Altogether, our finding suggests that the well-known finger/number interaction can be reversed with tool use.     

Young and older adults' strategies in complex arithmetic

Young and older adults solved complex addition problems such as 49 + 56. Verbal protocols, solution times, and percentage errors documented strategy repertoire and strategy selection in young and older participants and age-related differences in complex arithmetic performance. Both young and older adults used a set of 9 strategies to solve complex addition problems, although many older adults used a smaller strategy repertoire. The data also showed age-related differences in strategy execution and strategy selection. We discuss general implications of the present data to further our understanding of complex arithmetic and the role of strategic variations during aging.     

Letter perception: from pixels to pandemonium

In 1959, Oliver Selfridge proposed a model of letter perception, the Pandemonium model, in which the central hypothesis was that letters are identified via their component features. Although a consensus developed around this general approach over the years, key evidence in its favor remained lacking. Recent research has started to provide important evidence in favor of feature-based letter perception, describing the nature of the features, and the time-course of processes involved in mapping features onto abstract letter identities. There is now hope that future 'pandemonium-like' models will be able to account for the rich empirical database on letter identification that has accumulated over the past 50 years, hence solving one key component of the reading process.     

Maternal odor shapes rapid face categorization in the infant brain

To successfully interact with a rich and ambiguous visual environment, the human brain learns to differentiate visual stimuli and to produce the same response to subsets of these stimuli despite their physical difference. Although this visual categorization function is traditionally investigated from a unisensory perspective, its early development is inherently constrained by multisensory inputs. In particular, an early‐maturing sensory system such as olfaction is ideally suited to support the immature visual system in infancy by providing stability and familiarity to a rapidly changing visual environment. Here, we test the hypothesis that rapid visual categorization of salient visual signals for the young infant brain, human faces, is shaped by another highly relevant human‐related input from the olfactory system, the mother's body odor. We observe that a right‐hemispheric neural signature of single‐glance face categorization from natural images is significantly enhanced in the maternal versus a control odor context in individual 4‐month‐old infant brains. A lack of difference between odor conditions for the common brain response elicited by both face and non‐face images rules out a mere enhancement of arousal or visual attention in the maternal odor context. These observations show that face‐selective neural activity in infancy is mediated by the presence of a (maternal) body odor, providing strong support for multisensory inputs driving category acquisition in the developing human brain and having important implications for our understanding of human perceptual development.     

Insensitivity of visual short-term memory to irrelevant visual information

Several authors have hypothesized that visuo-spatial working memory is functionally analogous to verbal working memory. Irrelevant background speech impairs verbal short-term memory. We investigated whether irrelevant visual information has an analogous effect on visual short-term memory, using a dynamic visual noise (DVN) technique known to disrupt visual imagery (Quinn & McConnell, 1996b). Experiment 1 replicated the effect of DVN on pegword imagery. Experiments 2 and 3 showed no effect of DVN on recall of static matrix patterns, despite a significant effect of a concurrent spatial tapping task. Experiment 4 showed no effect of DVN on encoding or maintenance of arrays of matrix patterns, despite testing memory by a recognition procedure to encourage visual rather than spatial processing. Serial position curves showed a one-item recency effect typical of visual short-term memory. Experiment 5 showed no effect of DVN on short-term recognition of Chinese characters, despite effects of visual similarity and a concurrent colour memory task that confirmed visual processing of the characters. We conclude that irrelevant visual noise does not impair visual short-term memory. Visual working memory may not be functionally analogous to verbal working memory, and different cognitive processes may underlie visual short-term memory and visual imagery.     

Mathematical Intuition and the Cognitive Roots of Mathematical Concepts

The foundation of Mathematics is both a logico-formal issue and an epistemological one. By the first, we mean the explicitation and analysis of formal proof principles, which, largely a posteriori, ground proof on general deduction rules and schemata. By the second, we mean the investigation of the constitutive genesis of concepts and structures, the aim of this paper. This “genealogy of concepts”, so dear to Riemann, Poincaré and Enriques among others, is necessary both in order to enrich the foundational analysis with an often disregarded aspect (the cognitive and historical constitution of mathematical structures) and because of the provable incompleteness of proof principles also in the analysis of deduction. For the purposes of our investigation, we will hint here to a philosophical frame as well as to some recent experimental studies on numerical cognition that support our claim on the cognitive origin and the constitutive role of mathematical intuition.     

Narrative identity in schizophrenia

This study examined narrative identity in a group of 81 patients with schizophrenia and 50 healthy controls through the recall of self-defining memories. The results indicated that patients’ narratives were less coherent and elaborate than those of controls. Schizophrenia patients were severely impaired in the ability to make connections with the self and extract meaning from their memories, which significantly correlated with illness duration. In agreement with earlier research, patients exhibited an early reminiscence bump. Moreover, the period of the reminiscence bump, which is highly relevant for identity development, was characterized by fewer achievements and more life-threatening event experiences, compared with controls. A negative correlation was found between negative symptoms, number of self-event connections and specificity of narratives. Our results suggest that schizophrenia patients have difficulties to organize and extract meaning from their past experiences in order to create coherent personal narratives.