Abstract:How do humans compute approximate number? According to one influential theory, approximate number representations arise in the intraparietal sulcus and are amodal, meaning that they arise independent of any sensory modality. Alternatively, approximate number may be computed initially within sensory systems. Here we tested for sensitivity to approximate number in the visual system using steady state visual evoked potentials. We recorded electroencephalography from humans while they viewed dotclouds presented at… Show more
“…The SOC model used here and in the previous studies instantiates canonical computations such as spatial filtering, exponentiation and normalization that are common throughout cortex (Carandini and Heeger, 2011). However, unlike several previous studies (Guillaume et al, 2018;Park, 2018;Lucero et al, 2020;Van Rinsveld et al, 2020), we find only weak evidence of a number response in our occipitally focused RC1. For 8 of our 9 comparisons across our three experiments, the occipital component failed to produce a significant effect of numerosity.…”
Section: Discussioncontrasting
confidence: 50%
“…The topography of the response suggested that numerical magnitude is automatically extracted very early in the visual system (Guillaume et al, 2018). A similar topography was observed when rapidly alternating dot clouds of unequal number were used (Lucero et al, 2020). Computational modeling (Van Rinsveld et al, 2020) has shown that early visual cortex could signal the presence of a number oddball or number alternation independently of other correlated stimulus dimensions.…”
Non-symbolic number changes produce transient Event Related Potentials over parietal electrodes, while numerosity effects measured with Steady-State Visual Evoked Potentials (SSVEPs) appear to originate in occipital cortex. We hypothesized that the stimulation rates used in previous SSVEP studies may be too rapid to drive parietal numerosity mechanisms. Here we recorded SSVEPs and behavioral reports over a slower range of temporal frequencies than previously used. Isoluminant dot stimuli updated at a consistent “carrier” frequency (3-6 Hz) while periodic changes in numerosity (e.g. 8→5) formed an even slower “oddball” frequency (0.5-1 Hz). Each numerosity oddball condition had a matched control condition where the number of dots did not change. Carrier frequencies induced SSVEPs with midline occipital topographies that did not differentiate the presence or absence of numerosity oddballs. By contrast, SSVEPs at oddball frequencies had parietal topographies and responded more strongly when oddballs were present. Consistent with our hypothesis, numerosity effects were stronger at slower stimulation rates. In a second study, the numerosity change was either supra-threshold (e.g. 8→5 dots) or near the threshold required for detecting numerosity changes (e.g. 8→9 dots). We found robust parietal responses for the supra-threshold case only, indicating a numerical distance effect. A third study replicated the parietal oddball SSVEP effect across four distinct suprathreshold numerosity-change conditions and showed that number change direction does not influence the effect. These findings show that SSVEP oddball paradigms can probe parietal computations of abstract numerosity, and may provide a rapid, portable approach to quantifying number sense within educational settings.
“…The SOC model used here and in the previous studies instantiates canonical computations such as spatial filtering, exponentiation and normalization that are common throughout cortex (Carandini and Heeger, 2011). However, unlike several previous studies (Guillaume et al, 2018;Park, 2018;Lucero et al, 2020;Van Rinsveld et al, 2020), we find only weak evidence of a number response in our occipitally focused RC1. For 8 of our 9 comparisons across our three experiments, the occipital component failed to produce a significant effect of numerosity.…”
Section: Discussioncontrasting
confidence: 50%
“…The topography of the response suggested that numerical magnitude is automatically extracted very early in the visual system (Guillaume et al, 2018). A similar topography was observed when rapidly alternating dot clouds of unequal number were used (Lucero et al, 2020). Computational modeling (Van Rinsveld et al, 2020) has shown that early visual cortex could signal the presence of a number oddball or number alternation independently of other correlated stimulus dimensions.…”
Non-symbolic number changes produce transient Event Related Potentials over parietal electrodes, while numerosity effects measured with Steady-State Visual Evoked Potentials (SSVEPs) appear to originate in occipital cortex. We hypothesized that the stimulation rates used in previous SSVEP studies may be too rapid to drive parietal numerosity mechanisms. Here we recorded SSVEPs and behavioral reports over a slower range of temporal frequencies than previously used. Isoluminant dot stimuli updated at a consistent “carrier” frequency (3-6 Hz) while periodic changes in numerosity (e.g. 8→5) formed an even slower “oddball” frequency (0.5-1 Hz). Each numerosity oddball condition had a matched control condition where the number of dots did not change. Carrier frequencies induced SSVEPs with midline occipital topographies that did not differentiate the presence or absence of numerosity oddballs. By contrast, SSVEPs at oddball frequencies had parietal topographies and responded more strongly when oddballs were present. Consistent with our hypothesis, numerosity effects were stronger at slower stimulation rates. In a second study, the numerosity change was either supra-threshold (e.g. 8→5 dots) or near the threshold required for detecting numerosity changes (e.g. 8→9 dots). We found robust parietal responses for the supra-threshold case only, indicating a numerical distance effect. A third study replicated the parietal oddball SSVEP effect across four distinct suprathreshold numerosity-change conditions and showed that number change direction does not influence the effect. These findings show that SSVEP oddball paradigms can probe parietal computations of abstract numerosity, and may provide a rapid, portable approach to quantifying number sense within educational settings.
“…Since similar response patterns were observed on each of these medial occipital electrodes (see Supplementary Fig. 1 ), further analyses were limited to the electrode Oz for reasons of brevity and to be in accordance with previous studies consistently reporting large number-specific effects on that electrode (see e.g., 42 – 45 ). Figure 2 Brain responses to numerical changes for ( A ) the Dots condition and ( B ) the Pictures condition.…”
Section: Resultsmentioning
confidence: 72%
“…Many studies used the FPVS design to investigate neural discrimination of face identities 35 , 36 , facial expressions 37 , letters and words 38 , 39 , tool categories 40 , and digits 41 . We recently found 42 , 43 that FPVS can also provide a reliable electrophysiological measure of numerical discrimination independent from other visual properties (see also 44 , 45 ,for a similar observation). These findings make FPVS a valuable tool to measure numerical discrimination without requiring any explicit task.…”
Humans have a Number Sense that enables them to represent and manipulate numerical quantities. Behavioral data suggest that the acuity of numerical discrimination is predictively associated with math ability—especially in children—but some authors argued that its assessment is problematic. In the present study, we used frequency-tagged electroencephalography to objectively measure spontaneous numerical discrimination during passive viewing of dot or picture arrays in healthy adults. During 1-min sequences, we introduced periodic numerosity changes and we progressively increased the magnitude of such changes every ten seconds. We found significant brain synchronization to the periodic numerosity changes from the 1.2 ratio over medial occipital regions, and amplitude strength increased with the numerical ratio. Brain responses were reliable across both stimulus formats. Interestingly, electrophysiological responses also mirrored performances on a number comparison task and seemed to be linked to math fluency. In sum, we present a neural marker of numerical acuity that is passively evaluated in short sequences, independent of stimulus format and that reflects behavioural performances on explicit number comparison tasks.
“…Conversely, for numerical ratios equal to and greater than 1.2, strong peaks were recorded in posterior regions, mostly in the medial occipital area centered around the electrodes Iz, O1, O2 and Oz (see Supplementary Table 1 for comparably lower frequency-tagged EEG responses in the left, medial, and right occipito-parietal cortices). Since similar response patterns were observed on each of these medial occipital electrodes (see Supplementary Figure 1), further analyses were limited to the electrode Oz for reasons of brevity and to be in accordance with previous studies consistently reporting large number-specific effects on that electrode (see e.g., Lucero et al, 2020;Park, 2017;Van Rinsveld et al, 2020). Figure 2 also depicts the average Signal-to-Noise Ratio (SNR, see Methods) of the EEG spectra recorded on the medial occipital electrode (Oz) for every ratio in the dots and pictures conditions.…”
Humans have a Number Sense that enables them to represent and manipulate numerical quantities. Behavioral data suggest that the acuity of numerical discrimination is predictively associated with math ability – especially in children – but some authors argued that its assessment is problematic. In the present study, we used frequency-tagged electroencephalography to objectively measure spontaneous numerical discrimination during passive viewing of dot or picture arrays. During only one-minute sequences, we introduced periodic numerosity changes and we progressively increased the magnitude of such changes every ten seconds. We found significant brain synchronization to the periodic numerosity changes from the 1.2 ratio over medial occipital regions, and amplitude strength increased with the numerical ratio. Crucially, electrophysiological responses significantly correlated with performance in a number comparison task and math fluency. This neural marker of numerical ability, passively evaluated in short sessions, could thus be of crucial interest to predict math ability in the future.
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