Recruitment of the occipital cortex by arithmetic processing follows computational bias in the congenitally blind.

Arithmetic reasoning activates the occipital cortex of congenitally blind people (CB). This activation of visual areas may highlight the functional flexibility of occipital regions deprived of their dominant inputs or relate to the intrinsic computational role of specific occipital regions. We contrasted these competing hypotheses by characterizing the brain activity of CB and sighted participants while performing subtraction, multiplication and a control letter task.

Detecting over-reporting of symptoms: the French version of the self-report symptom inventory.

Objective: Symptom exaggeration and malingering are core issues in forensic and clinical evaluation. Generally, experts use two main types of instruments to assess the credibility of symptoms: performance validity tests that aim to detect underperformance and self-report validity tests that appraise over-reporting of symptoms. However, while many tools can be used to assess underperformance, far fewer instruments are available to evaluate over-reporting of symptoms.

How should proxies of cognitive reserve be evaluated in a population of healthy older adults?

Background: While some tools have been developed to estimate an individual's cognitive reserve (CR), no study has assessed the adequacy of the method used for assessing these CR proxy indicators. Therefore, we aimed to determine the most appropriate method to estimate CR by comparing two approaches: (1) the common assessment of CR proxies in the literature (e.g.

Visual experience influences the interactions between fingers and numbers.

Though a clear interaction between finger and number representations has been demonstrated, what drives the development of this intertwining remains unclear. Here we tested early blind, late blind and sighted control participants in two counting tasks, each performed under three different conditions: a resting condition, a condition requiring hands movements and a condition requiring feet movements. In the resting condition, every sighted and late blind spontaneously used their fingers, while the majority of early blind did not.

The processing of symbolic and nonsymbolic ratios in school-age children.

This study tested the processing of ratios of natural numbers in school-age children. Nine- and eleven-year-olds were presented collections made up of orange and grey dots (i.e.

Increased sensitivity to proactive and retroactive interference in amnestic mild cognitive impairment: new insights.

Background: Increased sensitivity to proactive (PI) and retroactive (RI) interference has been observed in amnestic mild cognitive impairment (aMCI). PI and RI are often explained as being the result of a response competition mechanism. However, patients with aMCI are supposed to suffer mostly from encoding deficits.

Over-estimation in numerosity estimation tasks: more than an attentional bias?

Over- and under-estimation have been observed in numerosity estimation and approximate arithmetic tasks. Two different models have been proposed to account for these reverse patterns of performance: 1) the bi-directional mapping account (Crollen, Castronovo, & Seron, 2011); 2) the operational momentum hypothesis (McCrink, Dehaene, & Dehaene-Lambertz, 2007). Our study was designed to examine whether the operational momentum could account for the over-estimation found in numerosity estimation tasks.

Effect of cognitive load on working memory forgetting in aging.

Functional approaches to working memory (WM) have been proposed recently to better investigate "maintenance" and "processing" mechanisms. The cognitive load (CL) hypothesis presented in the "Time-Based Resource-Sharing" model (Barrouillet & Camos, 2007) suggests that forgetting from WM (maintenance) can be investigated by varying the presentation rate and processing speed (processing). In this study, young and elderly participants were compared on WM tasks in which the difference in processing speed was controlled by CL manipulations.

The mental representation of the magnitude of symbolic and nonsymbolic ratios in adults.

This study mainly investigated the specificity of the processing of fraction magnitudes. Adults performed a magnitude-estimation task on fractions, the ratios of collections of dots, and the ratios of surface areas. Their performance on fractions was directly compared with that on nonsymbolic ratios.

Embodied numbers: the role of vision in the development of number-space interactions.

The strong association between numbers and space is found in the well-documented SNARC effect (Spatial Numerical Association of Response Codes), where responses on small/large numbers are faster in the left/right side of space, respectively. However, little is known about the developmental process through which numbers are mapped onto external physical space. Here we show that early blind individuals, but not late blind or sighted, demonstrate a reversed SNARC effect when performing a numerical comparison task with hands crossed over the body midline.

The role of vision in the development of finger-number interactions: Finger-counting and finger-montring in blind children.

Previous research has suggested that the use of the fingers may play a functional role in the development of a mature counting system. However, the role of developmental vision in the elaboration of a finger numeral representation remains unexplored. In the current study, 14 congenitally blind children and 14 matched sighted controls undertook three different test batteries that examined (a) general cognitive abilities, (b) the spontaneous use of finger-counting and finger-montring strategies (where "finger-montring" is a term used to characterize the way people raise their fingers to show numerosities to other people), and (c) the canonicity level of the finger-counting and finger-montring habits.

Associative encoding deficits in amnestic mild cognitive impairment: a volumetric and functional MRI study.

Background: Previous functional MRI studies have shown increased hippocampus activation in response to item encoding in amnestic mild cognitive impairment (aMCI). Recent behavioral studies suggested that associative memory could be more impaired than item memory in aMCI. So far, associative encoding has not been evaluated separately from item encoding in functional MRI studies.

Superior estimation abilities in two autistic spectrum children.

Anecdotal reports of superior estimation abilities in autistic individuals (e.g., Sacks, 1985) have never been confirmed empirically.

Under- and over-estimation: a bi-directional mapping process between symbolic and non-symbolic representations of number?

Over the last 30 years, numerical estimation has been largely studied. Recently, Castronovo and Seron (2007) proposed the bi-directional mapping hypothesis in order to account for the finding that dependent on the type of estimation task (perception vs. production of numerosities), reverse patterns of performance are found (i.

Increased sensitivity to proactive interference in amnestic mild cognitive impairment is independent of associative and semantic impairment.

Episodic memory deficit is the hallmark of amnestic mild cognitive impairment (aMCI). There is, however, an overlap in performance among patients with aMCI and elderly controls (EC). The memory deficit in aMCI therefore needs to be better characterized.

Numerical estimation in blind subjects: evidence of the impact of blindness and its following experience.

Vision was for a long time considered to be essential in the elaboration of the semantic numerical representation. However, early visual deprivation does not seem to preclude the development of a spatial continuum oriented from left to right to represent numbers (J. Castronovo & X.

Contribution of hand motor circuits to counting.

The finding that number processing activates a cortical network partly overlapping that recruited for hand movements has renewed interest in the relationship between number and finger representations. Further evidence about a possible link between fingers and numbers comes from developmental studies showing that finger movements play a crucial role in learning counting. However, increased activity in hand motor circuits during counting may unveil unspecific processes, such as shifting attention, reciting number names, or matching items with a number name.

Semantic numerical representation in blind subjects: the role of vision in the spatial format of the mental number line.

Does vision play a role in the elaboration of the semantic representation of small and large numerosities, notably in its spatial format? To investigate this issue, we decided to compare in the auditory modality the performance of congenitally and early blind people with that of a sighted control group, in two number comparison tasks (to 5 and to 55) and in one parity judgement task. Blind and sighted participants presented exactly the same distance and SNARC (Spatial Numerical Association of Response Codes) effects, indicating that they share the same semantic numerical representation. In consequence, our results suggest that the spatial dimension of the numerical representation is not necessarily attributable to the visual modality and that the absence of vision does not preclude the elaboration of this representation for 1-digit (Experiment 1) and 2-digit numerosities (Experiment 2).

Finger-digit compatibility in Arabic numeral processing.

Finger-digit response compatibility was tested by asking participants to identify Arabic digits by pressing 1 of 10 keys with all 10 fingers. The direction of the finger-digit mapping was varied by manipulating the global direction of the hand-digit mapping as well as the direction of the finger-digit mapping within each hand (in each case, from small to large digits, or the reverse). The hypothesis of a left-to-right mental number line predicted that a complete left-to-right mapping should be easier whereas the hypothesis of a representation based on finger counting predicted that a counting-congruent mapping should be easier.

Numerical order and quantity processing in number comparison.

We investigated processing of numerical order information and its relation to mechanisms of numerical quantity processing. In two experiments, performance on a quantity-comparison task (e.g.

Numerosity-duration interference: a Stroop experiment.

The existence of a possible common mechanism for duration and numerosity processing was tested with a Stroop task. Participants had to compare either the duration or the numerosity of sequences of flashing dots for which the duration and numerosity were independently manipulated to create congruent, incongruent or neutral pairs. Results show that the numerical cues interfered with duration processing, whereas the temporal cues did not interfere with numerosity processing.

Hemispheric lateralization of number comparison.

In order to clarify the respective contribution of the right and left posterior parietal cortex (PPC) to number comparison, transcranial magnetic stimulation (TMS) was used to disrupt PPC processing in subjects instructed to determine whether a digit was smaller or larger than 5. Single pulse TMS was applied over the PPC, either unilaterally or bilaterally, 150, 200, or 250 ms after digit presentation. Sham TMS was used as a control condition to take into account the unspecific effects of TMS on reaction time (RT).

Task-independent semantic activation for numbers and animals.

Unlabelled: Semantic processing of numbers and animals was contrasted with PET in two different tasks (comparison and classification) to test the hypothesis that knowledge about numbers is associated with increased activation in the parietal cortices, regardless of the semantic task (i.e.

Classification: is seven odd? Comparison: is seven larger than 5?).