The impact of inhibition capacities on number-space associations in young and elderly adults

Poster (2013, February 26)

Background: Numerical and spatial representations are tightly linked, i.e. when doing a binary classification judgment on Arabic digits participants are faster to respond with their left/right hand to ... [more ▼]

Background: Numerical and spatial representations are tightly linked, i.e. when doing a binary classification judgment on Arabic digits participants are faster to respond with their left/right hand to small/large numbers respectively (SNARC effect, Dehaene et al., 1993). The SNARC effect has been extensively replicated but one of its characteristics remains inter-individual variability (Wood et al., 2006). Different sources have been proposed to account for the reported inter-individual variability, namely response speed (Gevers et al., 2006), inhibition capacities (Wood et al., 2008) and age (Wood et al., 2008). The present study aims to investigate the impact of inhibition capacities on the SNARC effect in young and elderly adults, controlling for individual general processing speed. Methods: Two groups of participants were included: young adults, N=28, mean age: 23 years (SD=3.02) and elderly adults, N=46, mean age: 65.9 years (SD=3.9). Participants performed a parity judgment SNARC paradigm as well as inhibition tests (Stroop, Incompatibility). General processing speed was evaluated using a simple shape matching task. Results: The two age-groups differed in the strength of the SNARC effect, inhibition capacities and processing speed, with the elderly adults displaying stronger SNARC effects, weaker inhibition capacities and slower processing speed. Correlation analysis including all participants confirmed these findings on an individual level by showing relations between the SNARC effect and age, as well as relations between the SNARC effect and both inhibition capacities (i.e. the Stroop effect) and processing speed. When controlling for processing speed, the relations between the SNARC effect and both inhibition capacities and age remained. Conversely, when controlling for inhibition capacities, only the relation between the SNARC effect and age (but not processing speed) remained significant, even when controlling in addition for processing speed. Relevance: By combining the variables age, inhibition capacities and individual processing speed, the present data are the first to reveal a strong link between inhibition capacities and number-space associations. Importantly, we demonstrate that this link is not mediated by general processing speed. Interestingly, the robust relation between the SNARC effect and age remains after controlling for processing speed and inhibition capacities, pointing to a new source of inter-individual differences in the strength of the SNARC effect that will need to be clarified in future research projects. [less ▲]

Mädchen und Jungen

in SCRIPT; EMACS (Eds.) PISA 2012. Nationaler Bericht Luxemburg (2013)

The interaction between number and space processing and math achievement in adults

Poster (2012, September 07)

Behavioral studies show a relation between numbers and space (for a review see De Hevia et al., 2008). One instance of this link is the SNARC (Spatial Numerical Association of Response Codes) effect ... [more ▼]

Behavioral studies show a relation between numbers and space (for a review see De Hevia et al., 2008). One instance of this link is the SNARC (Spatial Numerical Association of Response Codes) effect, consisting in faster reaction times responding to small/large digits with the left/right hand respectively (Dehaene et al. 1993). The SNARC effect has often been replicated, but it is also characterized by high inter-subject variability (Wood et al. 2006 a,b). Although differences in mathematical skills are an obvious candidate source for SNARC variability, this variable has not yet been explored systematically. For the present study, three groups of participants were recruited amongst University students; one group included only participants reporting specific problems related to numerical processing, and two control groups differing in the math requirements of their field of study (i.e. science students vs. literature students). Results confirmed that the three groups differed substantially in basic arithmetic scores [F(2,92)=19.97, p<0.001] as well as in the strength of their SNARC effect [F(2,92)=7.12, p=0.001]. The science group had the highest arithmetic score and the smallest SNARC effect and the problem report group had the lowest arithmetic score and the strongest SNARC effect, with the literature group lying in between. Rearranging the groups based on arithmetic performance yielded the same results. Correlation analyses confirmed this finding by revealing a strong relation between arithmetic scores and SNARC effect independently of group constitution [r=-0.28, p<0.01]. Different hypotheses in the context of the relevant literature are discussed. [less ▲]

A developmental investigation of the SNARC effect using a colour discrimination task.

Presentation (2012, July 17)

How do number-space interactions develop from childhood to adulthood? The SNARC effect (Spatial Numerical Association of Response Codes) reflects the finding that participants respond faster to small ... [more ▼]

How do number-space interactions develop from childhood to adulthood? The SNARC effect (Spatial Numerical Association of Response Codes) reflects the finding that participants respond faster to small numbers with their left hand and to large numbers with their right hand during a number classification task. Typically assessed through magnitude-independent parity judgment tasks, the SNARC effect is thought to show the automaticity of the number-space link. Using a parity task on children Berch et al. (1999) found a SNARC effect no earlier than from 9.2 years onwards. However, we hypothesise that parity judgments might be inappropriate to assess younger children. Therefore a more age-apropriate colour judgment task (implicit) and a magnitude judgement task (explicit) were designed and tested on 363 children from kindergarten to Grade 6 (5.8-12 years). The experimental tasks were complemented by a brief assessment of arithmetic skills. The results revealed overall significant SNARC effects [colour task t(355)=2.6, p<0.01; magnitude task t(340)=4.7, p<0.001], which interacted with grade [colour task F(6,355)=2.18; p<0.05; magnitude task F(6,340)=2.09; p=0.05]. Most interestingly, even the kindergartners already display both effects [colour task t(28)=1.96; p<0.05; magnitude task t(24)=1.7; p=0.05]. These results show explicit and implicit access to numerical magnitude in children as young as 5.8 years. [less ▲]

Shifts of spatial attention cued by irrelevant numbers: Electrophysiological evidence from a target discrimination task

Poster (2012, February 10)

Fischer et al. demonstrated that a centrally presented number can shift attention to the left/right when its magnitude is small/large. Two electrophysiological studies described these attentional effects ... [more ▼]

Fischer et al. demonstrated that a centrally presented number can shift attention to the left/right when its magnitude is small/large. Two electrophysiological studies described these attentional effects as event-related potentials (ERPs) at centro-parietal sites. Since both studies used target detection tasks, it remains currently unknown whether similar results would be obtained with a discrimination task. We used ERPs to test whether digit cues also induce attention shifts when participants perform a feature-discrimination task on targets. ERPs were recorded whereas subjects discriminated the colour of lateral targets that were preceded by a central non-predictive digit. Analysis of cue-locked controlateral vs. ipsilateral ERP activity showed the emergence of early preparatory attention-directing components in parietal and frontal regions. Moreover, target-locked P1 components at occipito-parietal sites were significantly modulated by digit magnitude-target side congruency. These results demonstrate that irrelevant digit cues also bias sensory processing when embedded in a feature-discrimination task. [less ▲]

Shifts of spatial attention cued by irrelevant numbers: Electrophysiological evidence from a target discrimination task

Poster (2011, April)

Fischer et al. demonstrated that a centrally presented number can shift attention to the left/right when its magnitude is small/large. Two electrophysiological studies described these attentional effects ... [more ▼]

Fischer et al. demonstrated that a centrally presented number can shift attention to the left/right when its magnitude is small/large. Two electrophysiological studies described these attentional effects as event-related potentials (ERPs) at centro-parietal sites. Since both studies used target detection tasks, it remains currently unknown whether similar results would be obtained with a discrimination task. We used ERPs to test whether digit cues also induce attention shifts when participants perform a feature-discrimination task on targets. ERPs were recorded whereas subjects discriminated the colour of lateral targets that were preceded by a central non-predictive digit. Analysis of cue-locked controlateral vs. ipsilateral ERP activity showed the emergence of early preparatory attention-directing components in parietal and frontal regions. Moreover, target-locked P1 components at occipito-parietal sites were significantly modulated by digit magnitude-target side congruency. These results demonstrate that irrelevant digit cues also bias sensory processing when embedded in a feature-discrimination task. [less ▲]

Facilitation and inhibition of return using numbers as attentional cues

Poster (2011)

Behavioural studies have shown a relation between numbers and space (DeHevia et al., 2008). Fischer and colleagues (2003) showed that digits can act as central spatial cues in a target detection task ... [more ▼]

Behavioural studies have shown a relation between numbers and space (DeHevia et al., 2008). Fischer and colleagues (2003) showed that digits can act as central spatial cues in a target detection task, resulting in shorter reaction times (RT) for left-sided targets when preceded by small numbers and for right-sided targets when preceded by large numbers. This facilitation effect indicates that numbers orient visuo-spatial attention to the left or right hemifield, depending on their magnitude. To date no studies investigated whether this facilitation is followed by inhibition of return at longer intervals, as could be expected with visuo-spatial attention shifts. To this aim, we designed an analogous paradigm to Fischer et al.’s, introducing additional longer intervals. Participants (n=25) were presented a task irrelevant digit (1,2 vs. 8,9) for 400ms and had to detect a brief (100ms) lateral target appearing after a variable interval (100, 250, 500, 750, 1000, 1250ms). A 2x6 repeated measures ANOVA of mean RT, with congruency and interval as within-subject variables yielded a significant interaction (F(5,24)=2.3, p<0.05). As expected, targets were detected faster when appearing in the congruent (small-left, large-right) hemifield after 250ms. Using the regression method proposed by Lorch and Myers (1990), the slope at this interval was significantly negative (t(24)=1.70, p=0.05); indicating a facilitation for the detection of targets in the congruent hemifield) (cf. Fischer et al., 2003). At the 1250ms interval, targets were detected significantly slower when they appeared in the congruent compared to the incongruent hemifield (yielding significantly positive slopes at 1250ms: t(24)=2.68, p=0.007). These findings provide the first evidence that digits not only produce facilitation effects at shorter intervals, but also induce inhibitory effects at longer intervals, confirming the visuo-spatial nature of the attention shifts associated with Arabic digits. [less ▲]

Facilitation and inhibition of return using numbers as attentional cues

Poster (2011)

Behavioural studies have shown a relation between numbers and space (DeHevia et al., 2008). Fischer and colleagues (2003) showed that digits can act as central spatial cues in a target detection task ... [more ▼]

Behavioural studies have shown a relation between numbers and space (DeHevia et al., 2008). Fischer and colleagues (2003) showed that digits can act as central spatial cues in a target detection task, resulting in shorter reaction times (RT) for left-sided targets when preceded by small numbers and for right-sided targets when preceded by large numbers. This facilitation effect indicates that numbers orient visuo-spatial attention to the left or right hemifield, depending on their magnitude. To date no studies investigated whether this facilitation is followed by inhibition of return at longer intervals, as could be expected with visuo-spatial attention shifts. To this aim, we designed an analogous paradigm to Fischer et al.’s, introducing additional longer intervals. Participants (n=22) were presented a task irrelevant digit (1,2 vs. 8,9) for 400ms and had to detect a brief (100ms) lateral target appearing after a variable interval (100, 250, 500, 750, 1000, 1250ms). A 2x6 repeated measures ANOVA of mean RT, with congruency and interval as within-subject variables yielded a significant interaction (F(5,21)=2.59, p=0.03). As expected, targets were detected significantly faster when appearing in the congruent (small-left, large-right) hemifield after 250ms (t(21)=2.01, p=0.029) (cf. Fischer et al., 2003). At 1250ms interval, targets were detected significantly slower when they appeared in the congruent compared to the incongruent hemifield (t(21)=2.29, p=0.016). These findings provide the first evidence that digits not only produce facilitation effects at shorter intervals, but also induce inhibitory effects at longer intervals, confirming the visuo-spatial nature of the attention shifts associated with Arabic digits. [less ▲]

When small is left and large is right : Behavioural evidence for attentional shifts due to irrelevant numerical cues

Poster (2010)

Numerous behavioural studies indicate the existence of a link between numerical representations and visuo-spatial processes (for review see DeHevia et al., 2008). A striking demonstration of this link was ... [more ▼]

Numerous behavioural studies indicate the existence of a link between numerical representations and visuo-spatial processes (for review see DeHevia et al., 2008). A striking demonstration of this link was provided by Fischer and colleagues (2003), who reported that participants detect a target faster in the left hemifield, if preceded by a small number (e.g. 2 or 3) and faster in the right hemifield if preceded by a large number (e.g. 8 or 9). This is strong evidence that numbers orient visuo-spatial attention to the left or right hemifield, depending on their magnitude (e.g., small and large, respectively) (see also Galfano et al., 2006; Ristic et al., 2006). We designed a modified version of this target detection paradigm, by replacing the detection task with a target discrimination task (cf. Hommel et al., 2001). The participants (n=16) were presented 1 task irrelevant digit (1,2 vs. 8,9) for 400ms. After a variable inter-stimulus interval (500, 1000 or 2000ms), they had to discriminate the colour of a brief (100ms) lateral target. We hypothesized that the centrally presented numbers would induce an orientation of attention, in the same direction as the initial observations by Fischer et al. (2003). The current results indicate a significant effect, but only for the shortest digit-target interval (500ms). We observed a significant interaction between number magnitude (small/large) and side of target presentation (left/right) (F1,15 =7.784, p<0.014). These findings indicate that the attentional shifts induced by irrelevant numerical material are independent of the exact nature of target processing (discrimination vs. detection). [less ▲]