Abstract
Numerical representation is not restricted to sensory modalities. It remains unclear how numerosity processing in different modalities interacts within the brain. Moreover, the effect of continuous magnitudes presented in one modality on the representation of numerosity in another modality has not been well studied. By using event-related potential (ERP) and source localization analyses, the present study examined whether there was an interaction between auditory numerosity and continuous magnitude on visual numerosity representation. A visual dot array (visual standard stimulus) was preceded by sound in which numerosity (Multiple-tone vs. One-tone conditions) and magnitude (Loud-tone vs. Soft-tone conditions) information were manipulated. Then, another visual dot array (visual comparison stimulus) was presented, and participants were required to compare the numerosities of the visual dots. Behavioural results revealed that participants showed smaller just-noticeable differences (JNDs) when visual stimuli were preceded by multiple tones than those when visual stimuli were preceded by one tone. The subsequent ERP analysis of visual standard stimuli revealed that the peak amplitude of N1 was more negative under the Loud-tone condition than that under the Soft-tone condition, which could be related to better preparatory attention. Moreover, a significant interaction between auditory numerosity and magnitude was found within the P2p time window for the standard stimuli. Further source localization analysis identified the effect of N1 and P2p to be in the right middle frontal gyrus (MFG) and left inferior parietal lobule (IPL). The present study suggests that numerosity information presented in one sensory modality could spontaneously affect the numerical representation in another modality.
Highlights
Numerical representation is not restricted to sensory modalities
The present study aimed to investigate whether numerosity and magnitude information presented in one sensory modality could influence non-symbolic numerosity representation in another modality
Behavioural results demonstrated that auditory numerosity information (One-tone vs. Multiple-tone) could affect the just-noticeable differences (JNDs) of responses to visual dot arrays, but magnitude information did not (Soft-tone vs. Loud-tone)
Summary
Numerical representation is not restricted to sensory modalities. It remains unclear how numerosity processing in different modalities interacts within the brain. A visual dot array (visual standard stimulus) was preceded by sound in which numerosity (Multiple-tone vs One-tone conditions) and magnitude (Loud-tone vs Soft-tone conditions) information were manipulated Another visual dot array (visual comparison stimulus) was presented, and participants were required to compare the numerosities of the visual dots. Participants compared the numerosities of the stimuli, and their performance was measured with Weber fractions (an index indicating the acuity of numerical representation) and the points of subjective equality (PSEs) Their performance was better (lower Weber fraction) for auditory stimuli than for visual stimuli, and the performance of the cross-modal condition was between those of the visual and auditory conditions. The results reported faster responses in the congruent trials than in the incongruent trials when the numerosity of the target was task-irrelevant Their results suggested that numerosity information could be automatically processed when the participants were required to respond to the numerical value of the target. Recent studies showed that the processing of numerosity information is independent of the semantic numerical information of the stimuli and has a natural advantage over other stimuli properties, such as the area and density of the stimuli, in perceptual judgement (Anobile et al, 2019; Cicchini, Anobile, & Burr, 2016, 2019)
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