Biology subjects

Sathian, K.

Publications and source records attributed to Sathian, K..

12 recordsLinked to original sources

bioRxiv2026

Associations Between Shape Iconicity Ratings and Speech Acoustics: Comparing Real Words and Pseudowords

Iconicity in spoken language refers to the mapping of speech sounds to meaning. For example, the pseudoword "bouba" is judged to sound rounded, whereas the pseudoword "kiki" is judged to sound pointed (Ramachandran & Hubbard, 2001). Recent work has found systematic relationships between speech acoustics and iconicity ratings in various meaning domains, including shape. To control for confounding by semantic knowledge, much research on iconicity relies on pseudowords. However, the role of iconicity in conveying the meanings of real words is still poorly understood. Here, we compared the relationship between speech acoustics and shape iconicity ratings for both pseudowords and real words. In this experiment, participants rated real words and pseudowords for how rounded or pointed they sounded. We compared the relationship between 12 acoustic parameters and the rounded/pointed ratings for both words and pseudowords. We found that the correlations between these acoustic parameters and the ratings were similar for real words and pseudowords, providing key evidence that iconicity of real words is linked to speech acoustics.

neuroscience↗

bioRxiv2026

Iconic Sound-Shape Correspondences in Aphasia

PurposeTo examine speech iconicity for shape in aphasia, we compared iconicity ratings from people with aphasia to those from neurologically intact individuals and evaluated how iconicity relates to phonological and semantic processing profiles in aphasia. MethodEleven people with aphasia and 11 age- and gender-matched neurologically intact participants rated how rounded or pointed 50 auditory pseudowords sounded using a 5-point scale. Ratings from participants with aphasia were compared to predicted iconicity ratings derived from reference ratings from prior work and to ratings from neurologically intact participants. For each participant with aphasia, correlations between individual ratings and predicted ratings were related to measures of phonological and semantic processing. ResultsRatings from people with aphasia were significantly correlated with both the predicted ratings and the ratings from neurologically intact participants. The strength of the correlation between individual ratings and predicted ratings did not differ significantly between groups, although there was a trend toward weaker correlations in the aphasia group. There were indications that greater language impairment was associated with greater disruption of iconicity ratings; in particular, deficits in phonological segmentation and semantic processing were associated with reduced sensitivity to shape iconicity. ConclusionThese findings suggest that sensitivity to shape iconicity is preserved in individuals with aphasia to varying degrees. The specific nature of language impairment appears to play an important role in determining iconicity processing in aphasia.

neuroscience↗

bioRxiv2026

DECODING HOW THE SOUNDS OF WORDS AND PSEUDOWORDS SIGNIFY SHAPE: AN fMRI STUDY

Iconicity refers to systematic links between word form and meaning. Although evidence for iconicity in natural language continues to grow, its neural basis remains unclear. Using functional magnetic resonance imaging (fMRI) and multivariate pattern analysis (MVPA), we examined iconic shape associations of auditory real words and pseudowords. The pseudowords were matched to the real words in phonemic and phonotactic properties, while differing primarily in the absence of learned semantic representations. Participants listened to each item and judged whether it sounded rounded or pointed. Searchlight MVPA revealed significant decoding for both stimulus types. For real words, iconic shape associations were decoded above chance in regions associated with visual and haptic shape processing (left lateral occipital complex and left anterior intraparietal sulcus), visual imagery (bilateral precuneus), phonological processing (bilateral supramarginal gyri), and semantic processing (left middle frontal and right superior frontal gyri). For pseudowords, significant decoding was found in regions associated with multisensory feature organization (right posterior intraparietal sulcus) and language processing (left angular and inferior frontal gyri). Together, these findings provide evidence for neural mechanisms mediating iconic associations, with language-related areas involved for both real words and pseudowords, and visual processing for real words.

neuroscience↗

bioRxiv2024

Acoustic parameter combinations underlying mapping of auditory pseudoword sounds to multiple domains of meaning: a machine learning approach

In spoken language, iconicity, referring to the resemblance between the sound structure of words and their meaning, is often studied using pseudowords. Previously, we showed that representational dissimilarity matrices (RDMs) of the shape ratings of pseudowords correlated significantly with RDMs of acoustic parameters reflecting spectro-temporal variations; the ratings also correlated significantly with voice quality parameters. Here, we examined how perceptual ratings relate to these parameters of pseudowords across eight meaning domains. We largely replicated our previous findings for shape, while observing different patterns for other domains. Using a k-nearest-neighbor (KNN) machine-learning algorithm, we compared 4095 combinations of twelve acoustic parameters (3 spectro-temporal and 9 characterizing vocal quality) to determine the optimal combination associated with iconicity ratings in each domain. We found that iconic mappings were linked to domain-specific combinations of acoustic parameters. One spectro-temporal parameter, the fast Fourier transform, contributed to all domains, indicating the importance of time-varying spectral properties for iconicity judgments. We applied the KNN approach to generate shape ratings for 160 real words. These generated ratings strongly correlated with perceptual ratings of real words, indicating the value of the KNN approach to assess iconic mapping in natural languages. Our findings support the relevance of iconicity to language.

neuroscience↗

bioRxiv2024

DIFFERENTIAL CONTRIBUTIONS OF THE SPECTRO-TEMPORAL AND VOCAL CHARACTERISTICS OF AUDITORY PSEUDOWORDS TO MULTIPLE SOUND-SYMBOLIC MAPPINGS

In spoken language, iconic (sound-symbolic) words are those whose sounds convey their meaning. Iconicity is widespread in natural languages, whether signed or spoken, but its instantiation across different domains of meaning has not been systematically studied. Here, participants rated a set of 537 auditory pseudowords on opposing dimensions of eight different sound-symbolic domains: shape (rounded-pointed), roughness (smooth-rough), hardness (hard-soft), weight (light-heavy), size (small-big), brightness (bright-dark), arousal (calming-exciting), and valence (good-bad). Ratings showed cross-domain relationships, some mirroring those between corresponding physical domains, e.g. size and weight ratings were associated, reflecting a physical size-weight relationship, while others involved figurative relationships, e.g. bright/dark mapped onto good/bad, respectively. Using four separate multiple regression analyses, we found that the phonetic categories, phonemic associations, and acoustic associations at both the whole-item and segmental levels, formed unique sets with characteristic feature weightings for each meaning domain studied. For the majority (12 of 16 dimensions), the phonemic regression accounted for the most variance in the ratings, followed by the phonetic category, segmental acoustic and whole-item acoustic regressions. We conclude that pseudoword iconicity is present across a range of meaning domains, with domain-specific patterns of linguistic and acoustic properties. Linguistic characterizations best captured judgments of iconicity across domains, suggesting that these properties represent the bundles of acoustic, articulatory, and abstract linguistic factors that may underlie iconicity in spoken language.

neuroscience↗

bioRxiv2024

Phonetic underpinnings of sound symbolism across multiple domains of meaning

Sound symbolism occurs when the sound of a word alone can convey its meaning, e.g. balloon and spike sound rounded and pointed, respectively. Sound-symbolic correspondences are widespread in natural languages, but it is unclear how they are instantiated across different domains of meaning. Here, participants rated auditory pseudowords on opposing scales of seven different sound-symbolic domains: shape (rounded-pointed), texture (hard-soft), weight (light-heavy), size (small-big), brightness (bright-dark), arousal (calming-exciting), and valence (good-bad). Ratings showed cross-domain relationships, some mirroring those between corresponding physical domains, e.g. size and weight ratings were associated, reflecting a physical size-weight relationship, while others involved metaphorical mappings, e.g., bright/dark mapped onto good/bad, respectively. The phonetic features of the pseudowords formed unique sets with characteristic feature weightings for each domain and tended to follow the cross-domain ratings relationships. These results suggest that sound-symbolic correspondences rely on domain-specific patterns of phonetic features, with cross-domain correspondences reflecting physical or metaphorical relationships.

neuroscience↗

bioRxiv2024

Neurocognitive Mechanism of Radiologists Perceptual Errors: Results of Preliminary Studies

BackgroundThe most prevalent type of radiologist error is failing to detect abnormalities on images, the so-called "perceptual error." The prevalence of this type of false-negative (FN) error remains essentially unchanged since it was first described in 1949. PurposeThe purpose of this research is to identify a potential neurocognitive mechanism contributing to radiologists susceptibility to perceptual error, in order to inform intervention strategies to reduce such errors in practice. These experiments evaluated the relationship between brain network activation states and radiologists perceptual errors on two distinct visual tasks utilizing functional MRI (fMRI) and functional Near Infrared Spectroscopy (fNIRs). Materials and MethodsA prospective study consisting of three experiments was carried out on a small number of radiologist subjects. The first two experiments used fMRI, with participants performing two distinct types of visual tasks, respectively: the first was a task requiring subjects continuous attention and the second task required visual search. For the first of these experiments, simultaneous functional Near-Infrared Spectroscopic Imaging (fNIRs) was utilized along with fMRI. The second experiment was combined fMRI and eye-tracking. A third experiment using fNIRs alone was an observational study of subjects neurocognitive states during their usual practice. ResultsAn approximately threefold increased risk of FN perceptual errors (misses) was observed in the presence of a particular error-prone neurocognitive state (EPS) involving simultaneous co-activation of elements of the Default Mode Network (DMN) and Frontoparietal Network (FPN), which was detectable by both functional imaging modalities, with high concordance. EPS episodes appeared to be stochastic in occurrence, and occurred without operator awareness. We also found a high prevalence of the EPS in radiologists performing their normal interpretive tasks in their actual practice setting. ConclusionOur results suggest that dynamic interactions between brain networks leading to a particular error-prone state (EPS) may underlie a substantial fraction of radiologists perceptual errors. We demonstrate that this EPS can be detected unobtrusively in the clinical setting. These results suggest potential intervention strategies for perceptual error, the largest class of radiologist errors in practice. Key Results/HighlightsO_LIPeriodic episodes of a discrete neurocognitive state were observed in radiologists during specific visual tasks and in actual clinical settings. C_LIO_LIThere was an approximately threefold increased risk of perceptual error during this state. Most FN errors for the two visual tasks occurred during these brief episodes (p < 0.01). C_LIO_LIThere was also a highly significant anti-correlation of the prevalence of the error-prone neurocognitive state (EPS) with subject age (p < 0.001). C_LI ConflictsThe authors report no conflicts of interest or potential competing interests. Summary StatementWe report experimental results corelating perceptual errors by radiologists to episodic fluctuations in brain network activation, which appear to occur on a stochastic basis. These produce an error-prone neurocognitive state outside of operator awareness or control that is associated with an approximately threefold increase in the risk of perceptual error.

neuroscience↗

bioRxiv2023

NEURAL BASIS OF SOUND-SYMBOLIC PSEUDOWORD-SHAPE CORRESPONDENCES

Non-arbitrary mapping between the sound of a word and its meaning, termed sound symbolism, is commonly studied through crossmodal correspondences between sounds and visual shapes, e.g., auditory pseudowords, like mohloh and kehteh, are matched to rounded and pointed visual shapes, respectively. Here, we used functional magnetic resonance imaging (fMRI) during a crossmodal matching task to investigate the hypotheses that sound symbolism (1) involves language processing; (2) depends on multisensory integration; (3) reflects embodiment of speech in hand movements. These hypotheses lead to corresponding neuroanatomical predictions of crossmodal congruency effects in (1) the language network; (2) areas mediating multisensory processing, including visual and auditory cortex; (3) regions responsible for sensorimotor control of the hand and mouth. Right-handed participants (n = 22) encountered audiovisual stimuli comprising a simultaneously presented visual shape (rounded or pointed) and an auditory pseudoword ( mohloh or kehteh) and indicated via a right-hand keypress whether the stimuli matched or not. Reaction times were faster for congruent than incongruent stimuli. Univariate analysis showed that activity was greater for the congruent compared to the incongruent condition in the left primary and association auditory cortex, and left anterior fusiform/parahippocampal gyri. Multivoxel pattern analysis revealed higher classification accuracy for the audiovisual stimuli when congruent than when incongruent, in the pars opercularis of the left inferior frontal (Brocas area), the left supramarginal, and the right mid-occipital gyri. These findings, considered in relation to the neuroanatomical predictions, support the first two hypotheses and suggest that sound symbolism involves both language processing and multisensory integration. HIGHLIGHTSO_LIfMRI investigation of sound-symbolic correspondences between auditory pseudowords and visual shapes C_LIO_LIFaster reaction times for congruent than incongruent audiovisual stimuli C_LIO_LIGreater activation in auditory and visual cortices for congruent stimuli C_LIO_LIHigher classification accuracy for congruent stimuli in language and visual areas C_LIO_LISound symbolism involves language processing and multisensory integration C_LI

neuroscience↗

bioRxiv2020

Neural Basis of Olfactory and Trigeminal Integration

Humans naturally integrate signals from the olfactory and intranasal trigeminal systems. A tight interplay has been demonstrated between these two systems, and yet the underlying neural circuitry that mediates olfactory-trigeminal integration remains poorly understood. Using functional magnetic resonance imaging (fMRI), combined with psychophysics, this study investigated the neural mechanisms underlying olfactory-trigeminal integration. Fifteen participants with normal olfactory function performed a localization task with air-puff stimuli, phenylethyl alcohol (PEA; rose odor), or a combination thereof while being scanned. The ability to localize PEA to either nostril was at chance. Yet, its presence significantly improved the localization accuracy of weak, but not strong, air-puffs, relative to air-puff localization without concomitant PEA when both stimuli were delivered concurrently to the same nostril, but not when different nostrils received the two stimuli. This enhancement in localization accuracy, exemplifying the principles of spatial coincidence and inverse effectiveness in multisensory integration, was associated with multisensory integrative activity in the primary olfactory (POC), orbitofrontal (OFC), superior temporal (STC), inferior parietal (IPC) and cingulate cortices, and in the cerebellum. Multisensory enhancement in most of these regions, except the OFC, correlated with behavioral multisensory enhancement, as did increases in connectivity between some of these regions. We interpret these findings as indicating that the POC is part of a distributed brain network mediating integration between the olfactory and trigeminal systems. HIGHLIGHTSO_LIPsychophysical and neuroimaging study of olfactory-mechanosensory (OM) integration C_LIO_LIBehavior, cortical activity and network connectivity show OM integration C_LIO_LIOM integration obeys principles of inverse effectiveness and spatial coincidence C_LIO_LIBehavioral and neural measures of OM integration are correlated C_LI

neuroscience↗

bioRxiv2019

Olfactory Co-Stimulation Influences Intranasal Somatosensory Perception

Olfactory sensitivity is influenced by intranasal trigeminal sensation. For instance, sniffing is central to how humans and animals perceive odorants. Here, we investigated the influence of olfactory co-stimulation on the perception of intranasal somatosensory stimulation. In this study, twenty-two healthy human subjects, with normal olfactory function, performed a localization task for weak air-puff stimuli, in the presence or absence of a pure odorant, phenyl ethyl alcohol (PEA; rose odor). Visual cues were used to inform participants to briefly hold their breath while weak, poorly localizable, air-puffs and/or PEA were delivered to either nostril. Although PEA alone could not be localized, when accompanied by a weak air-puff in the ipsilateral nostril, localization accuracy significantly improved, relative to presentation of the air-puff without the odorant. The enhancement of localization was absent when the air-puff and PEA were presented to opposite nostril. Since ipsilateral but not contralateral co-stimulation with PEA increased the accuracy of weak air-puff localization, the results argue against a non-specific alerting effect of PEA. These findings suggest an interaction between the olfactory and somatosensory trigeminal systems.

neuroscience↗

bioRxiv2019

Acoustic and visual stimulus parameters underlying sound-symbolic crossmodal correspondences

It is often assumed that a fundamental property of language is the arbitrariness of the relationship between sound and meaning. Sound symbolism, which refers to non-arbitrary mapping between the sound of a word and its meaning, contradicts this assumption. Sensitivity to sound symbolism has been studied through crossmodal correspondences (CCs) between auditory pseudowords (e.g. loh-moh) and visual shapes (e.g. a blob). We used representational similarity analysis to examine the relationships between physical stimulus parameters and perceptual ratings that varied on dimensions of roundedness and pointedness, for a range of auditory pseudowords and visual shapes. We found that perceptual ratings of these stimuli relate to certain physical features of both the visual and auditory domains. Representational dissimilarity matrices (RDMs) of parameters that capture the spatial profile of the visual shapes, such as the simple matching coefficient and Jaccard distance, were significantly correlated with those of the visual ratings. RDMs of certain acoustic parameters of the pseudowords, such as the temporal fast Fourier transform (FFT) and spectral tilt, that reflect spectral composition, as well as shimmer and speech envelope that reflect aspects of amplitude variation over time, were significantly correlated with those of the auditory perceptual ratings. RDMs of the temporal FFT (acoustic) and the simple matching coefficient (visual) were significantly correlated. These findings suggest that sound-symbolic CCs are related to basic properties of auditory and visual stimuli, and thus provide insights into the fundamental nature of sound symbolism and how this might evoke specific impressions of physical meaning in natural language.

neuroscience↗

bioRxiv2018

Neural Basis Of The Sound-Symbolic Crossmodal Correspondence Between Auditory Pseudowords And Visual Shapes

Sound symbolism refers to the association between the sounds of words and their meanings, often studied using the crossmodal correspondence between auditory pseudowords, e.g. takete or maluma, and pointed or rounded visual shapes, respectively. In a functional magnetic resonance imaging study, participants were presented with pseudoword-shape pairs that were sound-symbolically congruent or incongruent. We found no significant congruency effects in the blood oxygenation level-dependent (BOLD) signal when participants were attending to visual shapes. During attention to auditory pseudowords, however, we observed greater BOLD activity for incongruent compared to congruent audiovisual pairs bilaterally in the intraparietal sulcus and supramarginal gyrus, and in the left middle frontal gyrus. We compared this activity to independent functional contrasts designed to test competing explanations of sound symbolism, but found no evidence for mediation via language, and only limited evidence for accounts based on multisensory integration and a general magnitude system. Instead, we suggest that the observed incongruency effects are likely to reflect phonological processing and/or multisensory attention. These findings advance our understanding of sound-to-meaning mapping in the brain.

neuroscience↗