Cross-modal Conditions Research Articles

Effects of intelligibility on within- and cross-modal sentence recognition memory

Listener-oriented speaking style adaptations improve sentence recognition memory in quiet and in noise (Van Engen et al. 2012, Gilbert et al. 2014). It is not clear if this advantage arises from the available cognitive resources, or enhanced memory traces. The present study investigated what may underlie the improved recognition memory for clear speech. In the within-modal condition, monolingual English listeners heard a total of 40 unique meaningful sentences in conversational and clear speaking styles, followed by a test phase in which they identified 80 audio sentences as old or new. In the cross-modal condition, the acoustic input in the test phase was replaced by written text. Results showed that while accuracy was high in both conditions, conversational-to-clear speech modifications significantly improved sentence recognition memory only in the within-modal condition. In the cross-modal condition, speaking style had no effect on sentence recognition memory. The results suggest that the benefit of clear speech over conversational speech on recognition memory lies in exaggerated acoustic-phonetic cues whose presence is necessary to activate memory traces. Speaking style adaptations may promote the encoding and storing of lower-level acoustic information rather than higher-level semantic information.

The Rewarding Effect of Pictures with Positive Emotional Connotation upon Perception and Processing of Pleasant Odors-An FMRI Study.

This fMRI study was designed to investigate the effect of cross-modal conditioning in 28 female volunteers. Subjects underwent initial fMRI block design scanning during which three pleasant olfactory stimuli were presented and had to be rated with respect to intensity and pleasantness. This was followed by an odor identification task spread out over 3 days: the experimental group was rewarded for successful trials (correct odor identification) with emotionally salient photos, whilst the control group only received randomly displayed, emotionally neutral, pictures. In the final scanning session, the odors were again presented, and subjects rated pleasantness and intensity. Both pleasantness ratings and fMRI data showed effects of the rewarding procedure. Activation in nucleus accumbens and the orbitofrontal cortex confirmed the hypothesis that learnt association of odors with visual stimuli of emotionally positive valence not only increases pleasantness of the olfactory stimuli but is also reflected in the activation of brain structures relevant for hedonic and reward processing. To our knowledge, this is the first paper to report successful cross-modal conditioning of olfactory stimuli with visual clues.

Activation in the angular gyrus and in the pSTS is modulated by face primes during voice recognition.

The aim of the present study was to better understand the interaction of face and voice processing when identifying people. In a S1-S2 crossmodal priming fMRI experiment, the target (S2) was a disyllabic voice stimulus, whereas the modality of the prime (S1) was manipulated blockwise and consisted of the silent video of a speaking face in the crossmodal condition or of a voice stimulus in the unimodal condition. Primes and targets were from the same speaker (person-congruent) or from two different speakers (person-incongruent). Participants had to classify the S2 as either an old or a young person. Response times were shorter after a congruent than after an incongruent face prime. The right posterior superior temporal sulcus (pSTS) and the right angular gyrus showed a significant person identity effect (person-incongruent > person-congruent) in the crossmodal condition but not in the unimodal condition. In the unimodal condition, a person identity effect was observed in the bilateral inferior frontal gyrus. Our data suggest that both the priming with a voice and with a face result in a preactivated voice representation of the respective person, which eventually facilitates (person-congruent trials) or hampers (person-incongruent trials) the processing of the identity of a subsequent voice. This process involves activation in the right pSTS and in the right angular gyrus for voices primed by faces, but not for voices primed by voices. Hum Brain Mapp 38:2553-2565, 2017. © 2017 Wiley Periodicals, Inc.

Multisensory Bayesian Inference Depends on Synapse Maturation during Training: Theoretical Analysis and Neural Modeling Implementation.

Recent theoretical and experimental studies suggest that in multisensory conditions, the brain performs a near-optimal Bayesian estimate of external events, giving more weight to the more reliable stimuli. However, the neural mechanisms responsible for this behavior, and its progressive maturation in a multisensory environment, are still insufficiently understood. The aim of this letter is to analyze this problem with a neural network model of audiovisual integration, based on probabilistic population coding-the idea that a population of neurons can encode probability functions to perform Bayesian inference. The model consists of two chains of unisensory neurons (auditory and visual) topologically organized. They receive the corresponding input through a plastic receptive field and reciprocally exchange plastic cross-modal synapses, which encode the spatial co-occurrence of visual-auditory inputs. A third chain of multisensory neurons performs a simple sum of auditory and visual excitations. The work includes a theoretical part and a computer simulation study. We show how a simple rule for synapse learning (consisting of Hebbian reinforcement and a decay term) can be used during training to shrink the receptive fields and encode the unisensory likelihood functions. Hence, after training, each unisensory area realizes a maximum likelihood estimate of stimulus position (auditory or visual). In cross-modal conditions, the same learning rule can encode information on prior probability into the cross-modal synapses. Computer simulations confirm the theoretical results and show that the proposed network can realize a maximum likelihood estimate of auditory (or visual) positions in unimodal conditions and a Bayesian estimate, with moderate deviations from optimality, in cross-modal conditions. Furthermore, the model explains the ventriloquism illusion and, looking at the activity in the multimodal neurons, explains the automatic reweighting of auditory and visual inputs on a trial-by-trial basis, according to the reliability of the individual cues.

L1 English / L2 Spanish: Orthography–phonology activation without contrasts

We consider how orthography activates sounds that are in a noncontrastive relationship in the second language (L2) and for which only one variant exists in the first language (L1). Participants were L1 English / L2 Spanish and native Spanish listeners. Intervocalically, Spanish graphemes ‘b d g’ correspond phonetically to stops and approximants (e.g. lobo ‘wolf’, lo[β]o), and in English they correspond only to stops. In Experiment 1, native and L2 Spanish listeners completed cross-modal (written–auditory) and within modal (auditory) priming tasks. Prime-target pairs were counterbalanced for phonetic variant. The results for L2 listeners in the cross-modal condition showed a significant interaction between variant and mode. Experiment 2 used long-term repetition priming to tap into longer-term representations and test whether L1 orthography is activated even when it is not strictly necessary to complete the task. Results for L2 speakers showed priming by both phonetic variants while for native listeners, only approximants showed a priming effect.

To bridge or not to bridge the multisensory time gap: bimanual coordination to sound and touch with temporal lags.

Living in a complex and multisensory environment involves constant interaction between perception and action. There is evidence that multisensory integration is governed by temporal factors, such as physiological synchrony between cross-modal stimuli favouring multisensory benefit, and the existence of a range of asynchrony between the stimuli which affords their binding (the temporal window of integration). These factors were examined in this study in a bimanual sensorimotor synchronization task with cross-modal stimuli. Participants synchronized each hand to a pair of audio-tactile stimuli, in which the asynchrony between onsets of auditory and tactile stimuli was systematically manipulated. In cross-modal conditions, they were instructed to tap either to the auditory stimuli or to tactile stimuli. The results reported a temporal window of integration of 160ms centred around 40 and 80ms (tactile first). Moreover, the temporal interval between the auditory and tactile stimuli affected the stability of bimanual coordination and of synchronization exclusively when participants were instructed to synchronize with tactile stimuli. Overall, the results indicate that both physiological asynchrony and temporal window of integration apply to cross-modal integration in a bimanual synchronization task. In addition, it shows the effect of auditory dominance onto multisensory temporal processes. This study sheds light on the role of temporal factors in multisensory processes when perception and actions are rhythmic and coupled.

Is impaired joint attention present in non-clinical individuals with high autistic traits?

BackgroundJoint attention skills are impaired in individuals with autism spectrum disorder (ASD). Recently, varying degrees of autistic social attention deficit have been detected in the general population. We investigated gaze-triggered attention in individuals with high and low levels of autistic traits under visual–auditory cross-modal conditions, which are more sensitive to social attention deficits than unimodal paradigms.MethodsSixty-six typically developing adults were divided into low- and high-autistic-trait groups according to scores on the autism-spectrum quotient (AQ) questionnaire. We examined gaze-triggered attention under visual–auditory cross-modal conditions. Two sounds (a social voice and a non-social tone) were manipulated as targets to infer the relationship between the cue and the target. Two types of stimulus onset asynchrony (SOA) conditions (a shorter 200-ms SOA and a longer 800-ms SOA) were used to directly test the effect of gaze cues on the detection of a sound target across different temporal intervals.ResultsIndividuals with high autistic traits (high-AQ group) did not differ from those with low autistic traits (low-AQ group) with respect to gaze-triggered attention when voices or tones were used as targets under the shorter SOA condition. In contrast, under the longer SOA condition, gaze-triggered attention was not observed in response to tonal targets among individuals in the high-AQ group, whereas it was observed among individuals in the low-AQ group. The results demonstrated that cross-modal gaze-triggered attention is short-lived in individuals with high autistic traits.ConclusionsThis finding provides insight into the cross-modal joint attention function among individuals along the autism spectrum from low autistic traits to ASD and may further our understanding of social behaviours among individuals at different places along the autistic trait continuum.

Precision and Bias in Approximate Numerical Judgment in Auditory, Tactile, and Cross-modal Presentation.

Many studies have claimed that the numerosity of any set of discrete elements can be depicted by a genuinely abstract number representation, irrespective of whether they are presented in a visual, auditory, or tactile modality. However, in behavioral studies, some inconsistencies have been observed in the performance of number comparisons among different modalities. In this study, we have tested whether numerical comparisons of auditory, tactile, and cross-modal presentations would differ under adequate control of stimulus presentation, and, if so, how they would differ. The unimodal and cross-modal stimuli pairs were presented in sequential manner. We measured the Weber fractions (i.e., precision) and points of subjective equality (i.e., accuracy) of numerical discriminations in auditory, tactile, and crossmodal conditions. The results showed that the Weber fractions are constant over standard stimuli, indicating that the Weber's law holds for the range of numerical values that was tested. Furthermore, the Weber fractions are consistent over unimodal and cross-modal comparisons, and this indicates that there is no additional noise involved in the cross-modal comparisons. Interestingly, the bias measure showed that the number of auditory stimuli is systematically overestimated compared with that of tactile stimuli.

Compensating for age limits through emotional crossmodal integration.

Social interactions in daily life necessitate the integration of social signals from different sensory modalities. In the aging literature, it is well established that the recognition of emotion in facial expressions declines with advancing age, and this also occurs with vocal expressions. By contrast, crossmodal integration processing in healthy aging individuals is less documented. Here, we investigated the age-related effects on emotion recognition when faces and voices were presented alone or simultaneously, allowing for crossmodal integration. In this study, 31 young adults (M = 25.8 years) and 31 older adults (M = 67.2 years) were instructed to identify several basic emotions (happiness, sadness, anger, fear, disgust) and a neutral expression, which were displayed as visual (facial expressions), auditory (non-verbal affective vocalizations) or crossmodal (simultaneous, congruent facial and vocal affective expressions) stimuli. The results showed that older adults performed slower and worse than younger adults at recognizing negative emotions from isolated faces and voices. In the crossmodal condition, although slower, older adults were as accurate as younger except for anger. Importantly, additional analyses using the “race model” demonstrate that older adults benefited to the same extent as younger adults from the combination of facial and vocal emotional stimuli. These results help explain some conflicting results in the literature and may clarify emotional abilities related to daily life that are partially spared among older adults.

Cross-modal and intra-modal binding between identity and location in spatial working memory: The identity of objects does not help recalling their locations

In this study we tested incidental feature-to-location binding in a spatial task, both in unimodal and cross-modal conditions. In Experiment 1 we administered a computerised version of the Corsi Block-Tapping Task (CBTT) in three different conditions: the first one analogous to the original CBTT test; the second one in which locations were associated with unfamiliar images; the third one in which locations were associated with non-verbal sounds. Results showed no effect on performance by the addition of identity information. In Experiment 2, locations on the screen were associated with pitched sounds in two different conditions: one in which different pitches were randomly associated with locations and the other in which pitches were assigned to match the vertical position of the CBTT squares congruently with their frequencies. In Experiment 2 we found marginal evidence of a pitch facilitation effect in the spatial memory task. We ran a third experiment to test the same conditions of Experiment 2 with a within-subject design. Results of Experiment 3 did not confirm the pitch–location facilitation effect. We concluded that the identity of objects does not affect recalling their locations. We discuss our results within the framework of the debate about the mechanisms of “what” and “where” feature binding in working memory.

Visual attention in a visual-haptic, cross-modal matching task in children and adults.

Visual fixation patterns were analyzed to gain insight into developmental changes in attention allocation in a cross-modal task. Two patterns that have been associated with increased task difficulty, gaze aversion and fixation duration, were recorded using an eye-tracker. In this exploratory study, 37 elementary age children (M age 7-10 yr.) and 23 undergraduates engaged in visual-only and haptic-visual shape-matching tasks. Theoretical assumptions underlying this study are that children have greater limitations on attention capacity compared to adults, and that a task presented in the cross-modal condition would pose special demands on this capacity. A 2×2 (uni- or cross-modal×age group) repeated-measures analysis of variance (ANOVA) was used to analyze both gaze aversion and average fixation duration. Children averted gaze significantly more during the cross-modal condition, supporting the idea that children use gaze aversion as an attention-shifting mechanism. Mean fixation duration increased for both groups in the cross-modal condition. Due to the small number and limited age range of the children as well as the limited number of task items, interpretations are made with caution.

Visual, haptic and bimodal scene perception: Evidence for a unitary representation

Participants studied seven meaningful scene-regions bordered by removable boundaries (30s each). In Experiment 1 (N=80) participants used visual or haptic exploration and then minutes later, reconstructed boundary position using the same or the alternate modality. Participants in all groups shifted boundary placement outward (boundary extension), but visual study yielded the greater error. Critically, this modality-specific difference in boundary extension transferred without cost in the cross-modal conditions, suggesting a functionally unitary scene representation. In Experiment 2 (N=20), bimodal study led to boundary extension that did not differ from haptic exploration alone, suggesting that bimodal spatial memory was constrained by the more “conservative” haptic modality. In Experiment 3 (N=20), as in picture studies, boundary memory was tested 30s after viewing each scene-region and as with pictures, boundary extension still occurred. Results suggest that scene representation is organized around an amodal spatial core that organizes bottom-up information from multiple modalities in combination with top-down expectations about the surrounding world.

Independent effects of bottom-up temporal expectancy and top-down spatial attention. An audiovisual study using rhythmic cueing.

Selective attention to a spatial location has shown enhanced perception and facilitate behavior for events at attended locations. However, selection relies not only on where but also when an event occurs. Recently, interest has turned to how intrinsic neural oscillations in the brain entrain to rhythms in our environment, and, stimuli appearing in or out of sync with a rhythm have shown to modulate perception and performance. Temporal expectations created by rhythms and spatial attention are two processes which have independently shown to affect stimulus processing but it remains largely unknown how, and if, they interact. In four separate tasks, this study investigated the effects of voluntary spatial attention and bottom-up temporal expectations created by rhythms in both unimodal and crossmodal conditions. In each task the participant used an informative cue, either color or pitch, to direct their covert spatial attention to the left or right, and respond as quickly as possible to a target. The lateralized target (visual or auditory) was then presented at the attended or unattended side. Importantly, although not task relevant, the cue was a rhythm of either flashes or beeps. The target was presented in or out of sync (early or late) with the rhythmic cue. Results showed participants were faster responding to spatially attended compared to unattended targets in all tasks. Moreover, there was an effect of rhythmic cueing upon response times in both unimodal and crossmodal conditions. Responses were faster to targets presented in sync with the rhythm compared to when they appeared too early in both crossmodal tasks. That is, rhythmic stimuli in one modality influenced the temporal expectancy in the other modality, suggesting temporal expectancies created by rhythms are crossmodal. Interestingly, there was no interaction between top-down spatial attention and rhythmic cueing in any task suggesting these two processes largely influenced behavior independently.

Isomorphic categories.

Learning and transfer were investigated for a categorical structure that could be mapped without loss of information from 1 sensory modality to another. The category space was composed of 3 nonoverlapping, linearly separable categories whose members were structured, temporal events. Each stimulus was composed of a sequence of on-off events that varied in duration and number of subevents (complexity). Categories were learned visually, haptically, or auditorily and transferred to the same or another modality. Despite the.isomorphism across modalities, significant differences appeared in both learning and transfer. The visual modality showed an early learning advantage, with information on the transfer test preserved best when encoded visually during learning, worst when encoded haptically, with auditory encoding intermediate. False recognition rates were elevated when categories were learned haptically and transferred to another modality. In general, classification accuracy was highest for the category prototype, with false recognition of the category prototype higher in the cross-modality conditions. The results are discussed in terms of current theories in modality transfer including the difficulties inherent when calculation of similarity must be considered in a cross-modal situation.

Atypical crossmodal emotional integration in patients with gliomas

The relevance of emotional perception in interpersonal relationships and social cognition has been well documented. Although brain diseases might impair emotional processing, studies concerning emotional recognition in patients with brain tumours are relatively rare. The aim of this study was to explore emotional recognition in patients with gliomas in three conditions (visual, auditory and crossmodal) and to analyse how tumour-related variables (notably, tumour localisation) and patient-related variables influence emotion recognition. Twenty six patients with gliomas and 26 matched healthy controls were instructed to identify 5 basic emotions and a neutral expression, which were displayed through visual, auditory and crossmodal stimuli. Relative to the controls, recognition was weakly impaired in the patient group under both visual and auditory conditions, but the performances were comparable in the crossmodal condition. Additional analyses using the ‘race model’ suggest differences in multisensory emotional integration abilities across the groups, which were potentially correlated with the executive disorders observed in the patients. These observations support the view of compensatory mechanisms in the case of gliomas that might preserve the quality of life and help maintain the normal social and professional lives often observed in these patients.

Silent music reading: Auditory imagery and visuotonal modality transfer in singers and non-singers

In daily life, responses are often facilitated by anticipatory imagery of expected targets which are announced by associated stimuli from different sensory modalities. Silent music reading represents an intriguing case of visuotonal modality transfer in working memory as it induces highly defined auditory imagery on the basis of presented visuospatial information (i.e. musical notes). Using functional MRI and a delayed sequence matching-to-sample paradigm, we compared brain activations during retention intervals (10s) of visual (VV) or tonal (TT) unimodal maintenance versus visuospatial-to-tonal modality transfer (VT) tasks. Visual or tonal sequences were comprised of six elements, white squares or tones, which were low, middle, or high regarding vertical screen position or pitch, respectively (presentation duration: 1.5s). For the cross-modal condition (VT, session 3), the visuospatial elements from condition VV (session 1) were re-defined as low, middle or high “notes” indicating low, middle or high tones from condition TT (session 2), respectively, and subjects had to match tonal sequences (probe) to previously presented note sequences. Tasks alternately had low or high cognitive load. To evaluate possible effects of music reading expertise, 15 singers and 15 non-musicians were included. Scanner task performance was excellent in both groups. Despite identity of applied visuospatial stimuli, visuotonal modality transfer versus visual maintenance (VT>VV) induced “inhibition” of visual brain areas and activation of primary and higher auditory brain areas which exceeded auditory activation elicited by tonal stimulation (VT>TT). This transfer-related visual-to-auditory activation shift occurred in both groups but was more pronounced in experts. Frontoparietal areas were activated by higher cognitive load but not by modality transfer. The auditory brain showed a potential to anticipate expected auditory target stimuli on the basis of non-auditory information and sensory brain activation rather mirrored expectation than stimulation. Silent music reading probably relies on these basic neurocognitive mechanisms.

The attentional‐relevance and temporal dynamics of visual‐tactile crossmodal interactions differentially influence early stages of somatosensory processing

BackgroundCrossmodal interactions between relevant visual and tactile inputs can enhance attentional modulation at early stages in somatosensory cortices to achieve goal-oriented behaviors. However, the specific contribution of each sensory system during attentional processing remains unclear. We used EEG to investigate the effects of visual priming and attentional relevance in modulating somatosensory cortical responses.MethodsHealthy adults performed a sensory integration task that required scaled motor responses dependent on the amplitudes of tactile and visual stimuli. Participants completed an attentional paradigm comprised of 5 conditions that presented sequential or concurrent pairs of discrete stimuli with random amplitude variations: 1) tactile-tactile (TT), 2) visual-visual (VV), 3) visual-tactile simultaneous (SIM), 4) tactile-visual delay (TVd), and 5) visual-tactile delay (VTd), each with a 100 ms temporal delay between stimulus onsets. Attention was directed to crossmodal conditions and graded motor responses representing the summation of the 2 stimulus amplitudes were made.ResultsResults of somatosensory ERPs showed that the modality-specific components (P50, P100) were sensitive to i) the temporal dynamics of crossmodal interactions, and ii) the relevance of these sensory signals for behaviour.ConclusionNotably, the P50 amplitude was greatest in the VTd condition, suggesting that presentation of relevant visual information for upcoming movement modulates somatosensory processing in modality-specific cortical regions, as early as the primary somatosensory cortex (SI).

Contrasting Effects of Dual-task Paradigm and of Timing Interruption Paradigm in Interval Timing of the Context of Culti-modal Processing

Distribution of attention in time information processing is one of the hot areas of research science, and the dual-task paradigm is one of the most common ways to study distribution of attention. It requires an individual to perform two tasks simultaneously, the less the attention allocated to a temporal interval, the shorter it is judged(Brown, 1997). The attention sharing effect is discussed within the framework of the scalar expectancy model of timing. In such paradigm the parallel processing itself may interfere with time perception and lead to unexpected deviations. In order to avoid such interference, the timing interruption paradigm would be a better solution as it uses a blank interruption instead. The researchers consistently found a similar position and interruption effect in both paradigms (Casini Macar, 1997; Cortin, Remblai,, 2006; Remblai, Cortin,, 2003). Furthermore, the results showed both the discontinuity and interference of current information processingwere belong to interruption effect, but to varying extents (Cortin, Masse, 2000; Macar, 2002). However, though the position and interruption effect were similar in the two paradigms, they have not been explored in a same stimuli series. As we know, information exchange with the outside world is not dependent on single sensory channel, but rather the interaction of cross-modal information processing. It would be valuable to explore the position and interruption effect in the context ofcross-modal processing. It would not only help to uncover the cognitive mechanism of time processing, but also have important practical values as it is more similar with daily life. Therefore, the present study was designed to investigate the position and interruption effect in the two paradigms in the cross-modal conditions. To this end, the study consisted of two experiments. In experiment 1, 2500 ms and 4500 ms were set for the target time intervals, using the same stimulus sequence (visual presentation, with aural interruption), participants were allocated to control, break and interference condition respectively. In experiment 2,the target intervals were set to 1500 ms and 2500 ms. Results of experiment 1 showed that the interruption effect is more significant in break condition regardless of target time intervals. Furthermore, under the 2500ms, position effect were found in all three conditions, whereas under the 4500ms condition, the position effect only existed in the break condition. Experiment 2 found that there was position effect consistently, regardless of the interpolation conditions or target time intervals. Besides, the interrupt effect was more significant in the break condition. Such results imply that whether the position effect is the same in the two paradigms depends on the length ofthe target intervals to some extent. Besides, in the timing interruption paradigm, the break effect on timing is more significant than the interference effect in dual-task paradigm.

Can gaze-cueing be helpful for detecting sound in autism spectrum disorder?

Autism spectrum disorder (ASD) is a developmental disorder characterized by impaired social interaction, including joint attention, but psychological studies generally have reported intact gaze-triggered joint attention in ASD. These studies used a uni-modal paradigm (i.e. visual cue–target pairs) with eyes or faces as cues and letters or dots as targets. However, it has not been determined whether joint attention is impaired under cross-modal conditions in ASD, although cross-modal impairment has been reported. This study investigated joint attention in ASD under cross-modal conditions with gaze stimuli as visual cues and two kinds of sound (social voice or non-social tone) stimuli as targets. The task for the subject was to locate the target sound and click as soon and as accurately as possible. The ASD group was impaired in joint attention when a tone was used as the target, while both groups showed joint attention to a voice. The results suggest that cross-modal joint attention is impaired in the ASD group when the cue–target relationship is weak (i.e. social cue and non-social target) while it is unimpaired when there is a strong cue–target relationship (i.e. social cue and social target).

Is approximate numerical judgment truly modality-independent? Visual, auditory, and cross-modal comparisons

The numerosity of any set of discrete elements can be depicted by a genuinely abstract number representation, irrespective of whether they are presented in the visual or auditory modality. The accumulator model predicts that no cost should apply for comparing numerosities within and across modalities. However, in behavioral studies, some inconsistencies have been apparent in the performance of number comparisons among different modalities. In this study, we tested whether and how numerical comparisons of visual, auditory, and cross-modal presentations would differ under adequate control of stimulus presentation. We measured the Weber fractions and points of subjective equality of numerical discrimination in visual, auditory, and cross-modal conditions. The results demonstrated differences between the performances in visual and auditory conditions, such that numerical discrimination of an auditory sequence was more precise than that of a visual sequence. The performance of cross-modal trials lay between performance levels in the visual and auditory conditions. Moreover, the number of visual stimuli was overestimated as compared to that of auditory stimuli. Our findings imply that the process of approximate numerical representation is complex and involves multiple stages, including accumulation and decision processes.