Perceptual Categorization Task Research Articles

Compactness of Native Vowel Categories in Monolingual, Bilingual, and Multilingual Speakers: Is Category Compactness Affected by the Number of Languages Spoken?

Phonetic category compactness pertains to the degree of variation or dispersion within a specific category. Previous research has shown that more compact native (L1) categories in production have been related to the discrimination of non-native sounds in perception and production. The understanding of the factors influencing L1 category compactness remains limited. Some proposals suggest that compactness may be influenced by individual differences in cognitive processes. Alternatively, category compactness could be linked to linguistic factors, such as the number of languages spoken or the density of the phonological system. This study investigates the latter hypothesis. This study examined category compactness in perception for three L1 Spanish vowels /i/, /e/, and /a/ across four participant groups: 12 monolinguals, 31 functional monolinguals, 24 bilinguals, and 19 multilinguals. To measure compactness in perception, the study employed a perceptual categorization task consisting of synthesized variants of /i/, /e/, and /a/. Participants were asked to label these variants as either acceptable or unacceptable members of their L1 /i/, /e/, and /a/ categories. The findings revealed significant differences in category compactness between monolingual and bi/multilingual speakers. More specifically, bilingual and multilingual speakers had larger/less compact L1 vowel categories than monolinguals. The substantial variability in compactness across all groups suggests that compactness may be influenced by a range of other individual differences, besides the number of languages spoken.

Categorical Perception of Lexical Tones and Stops in Mandarin-Speaking Musicians and Nonmusicians

This study investigates the perception of Mandarin lexical tones and stops to examine the degree of overlap between music and language. Eighteen musicians and 21 nonmusicians participated in a typical categorical perception task. Results showed that musicians and nonmusicians had comparable degree of categorical perception of tones and stops. Compared to nonmusicians, musicians exhibited enhanced sensitivities to within-category lexical tone stimuli. However, this improved ability was not observed in the perception of stops. These findings imply that musical experience strengthens the acuity of subtle low-level acoustic variations between within-category lexical tone stimuli without interfering with the high-level phonological representations of lexical tones, and this facilitatory effect is selective and could not readily extend to stop consonants in native language.

Sociophonetic Variation in Vowel Categorization of Australian English.

This study involves a perceptual categorization task for Australian English, designed to investigate regional and social variation in category boundaries between close-front vowel contrasts. Data are from four locations in southeast Australia. A total of 81 listeners from two listener groups took part: (a) so-called mainstream Australian English listeners from all four locations, and (b) L1 Aboriginal English listeners from one of the locations. Listeners heard front vowels /ɪ e æ/ arranged in 7-step continua presented at random. Varied phonetic contexts were analyzed, with a focus on coda /l/ because of a well-known prelateral merger of /e æ/ through mid-vowel lowering (e.g., celery-salary) reported to occur in some communities in this part of Australia. The results indicate that regional variation in Australian English is evident in perception. In particular, merging of /el/-/æl/ is shown to occur in the southernmost regions analyzed, but rarely in the northern regions of the geographical area under investigation. Aside from regional variation observed, age was also a factor in how participants responded to the task: older speakers had more merger than younger speakers in many locations, which is a new finding-previously, the merger was thought to be increasing in frequency over time, yet here we see this in only one location. Aboriginal English listeners also responded differently when compared with mainstream Australian English listeners. By analyzing the perception results across a variety of regional locations, with data from two different Australian social groups in the same location, this study adds a new dimension to our understanding of regional and social variations in Australian English.

Questioning questions - the perception of f0 scaling in German questions between categorical function and continuous attitude.

In previous studies comparing the intonation of questions and statements in German, greater f0 excursions of phrase-final rises have been associated with questions in both read speech and spontaneous speech. This holds for production studies as well as perception studies. However, a major question remains whether these differences are perceived categorically or continuously. Furthermore, we ask whether the differences in f0 scaling correspond to categorical linguistic functions or rather an attitudinal continuum. We conducted three different perception experiments: a classical categorical perception task, an imitation task, and a semantic evaluation task. The results suggest that f0 scaling in phrase-final rises is perceived as a phonetic continuum rather than in phonological categories. Furthermore, the gradual increase of the final rise is associated with a gradual increase in perceived questioning. Lastly, the phonetic cues to this degree of questioning are distinct from those to the other investigated meanings surprise and uncertainty. Accordingly, this study supports the assumption that questioning constitutes an attitudinal meaning in its own right.

Degree of Breathiness in a Synthesized Voice Signal as it Differentiates Masculine versus Feminine Voices

Most studies determining speakers' perceived gender as binarily female or male are reliant on F0 perception, although other vocal parameters may also contribute to the perception of gender. The current study focused on the impact of breathiness on the perception of speakers' gender as a biological variable (feminine or masculine). n=31 normal hearing, native English speakers, 18 female, 13 male, mean age 23 (SD=3.54), were auditorily and visually trained in and then took part in a categorical perception task. A continuum of nine samples of the word "hello", was created in an airway modulation model of speech and voice production. Resting vocal fold length, resting vocal fold thickness, F0, and vocal tract length were fixed. Glottal width at the vocal process, posterior glottal gap, and bronchial pressure were continually modified for all stimuli. Each stimulus was randomly presented 30 times within each of the fiveblocks (150 presentations in total). Participants rated stimuli as binarily female or male. Showed a sigmoidal shift in breathiness along the continuum between perceived feminine or masculine voicing. This shift was evident at stimuli four and five, indicating a nonlinear, discrete perception of breathiness among participants. Response times were also significantly slower in these two stimuli, suggesting a categorical perception of breathiness among participants. Breathiness created by the change in glottal width of at least 0.21cm may influence the perception of a speaker's perceived gender.

The excessive generalization of fear affected by perceptual bias in experimental pain individuals: Evidence from an event-related potential study.

Excessiv generalization of fear contributes to the development and maintenance of pain. Prior research has demonstrated the importance of perception in fear generalization and found that individuals in painful conditions exhibited perceptual bias. However, the extent to which perceptual bias in pain affects the generalization of pain-related fear and its underlying neural activity remains unclear. Here, we tested whether perceptual bias in experimental pain individuals led to the overgeneralization of pain-related fear by recording behavioral and neural responses. To this end, we established an experimental pain model by spraying capsaicin on the surface of the seventh cervical vertebra of the participant. A total of 23 experimental pain participants and 23 matched nonpain controls learned fear conditioning and then completed the fear generalization paradigm combined with the perceptual categorization task. We found that the novel and safety cues were more likely to be identified as threat cues in the experimental group, resulting in higher US expectancy ratings compared to the control group. The event-related potential results showed that the experimental group exhibited earlier N1 latency and smaller P1 and late positive potential amplitudes than those in the control group. Our findings suggest that the experimental pain individuals exhibited an excessive generalization of fear affected by perceptual bias and reduced their attentional allocation to pain-related fear stimuli.

Point estimate observers: A new class of models for perceptual decision making.

Bayesian optimal inference is often heralded as a principled, general framework for human perception. However, optimal inference requires integration over all possible world states, which quickly becomes intractable in complex real-world settings. Additionally, deviations from optimal inference have been observed in human decisions. A number of approximation methods have previously been suggested, such as sampling methods. In this study, we additionally propose point estimate observers, which evaluate only a single best estimate of the world state per response category. We compare the predicted behavior of these model observers to human decisions in five perceptual categorization tasks. Compared to the Bayesian observer, the point estimate observer loses decisively in one task, ties in two and wins in two tasks. Two sampling observers also improve upon the Bayesian observer, but in a different set of tasks. Thus, none of the existing general observer models appears to fit human perceptual decisions in all situations, but the point estimate observer is competitive with other observer models and may provide another stepping stone for future model development. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Deconstructing Mechanisms of Abnormal Categorical Perception of Emotional Facial Expressions in Schizophrenia Patients.

The current study aims to find out the potential reasons why most schizophrenia patients have a relatively low sensitivity to the classification of emotional facial expressions. By using an emotional categorical perception task, eighty-three schizophrenia patients and seventy-one healthy adults are provided with morphed emotional continuums with two emotional facial expressions (a positive emotional valence: happy; a negative emotional valence: sad). Through comparing the difference between schizophrenia patients and healthy adults in the processes of estimating facial expressions with ambiguous emotions, we find that the pattern of emotional categorical perception for schizophrenia patients is significantly different from that of healthy controls when they process signals on the local facial areas. Compared to healthy people, schizophrenia patients have a significantly separate classification pattern in processing emotional signals between the eyes and mouth regions. It indicates that compared to healthy adults, schizophrenia patients have larger conflicts in integrating emotional signals from different facial areas. To overcome conflicts, more cognitive resources are required. Unfortunately, the lack of cognitive resources leads to the failure of integration, which further increases the difficulty of estimating facial expressions with ambiguous emotions, and finally leads to the relatively low sensitivity of emotional facial expressions classification. To sum up, the deficit of abnormal perceptions of emotional facial expressions in schizophrenia patients results from an integrated deficit of signals on facial areas.

Developmental changes in the categorization of speech and song.

Music and language are two fundamental forms of human communication. Many studies examine the development of music- and language-specific knowledge, but few studies compare how listeners know they are listening to music or language. Although we readily differentiate these domains, how we distinguish music and language-and especially speech and song- is not obvious. In two studies, we asked how listeners categorize speech and song. Study 1 used online survey data to illustrate that 4- to 17-year-olds and adults have verbalizable distinctions for speech and song. At all ages, listeners described speech and song differences based on acoustic features, but compared with older children, 4- to 7-year-olds more often used volume to describe differences, suggesting that they are still learning to identify the features most useful for differentiating speech from song. Study 2 used a perceptual categorization task to demonstrate that 4-8-year-olds and adults readily categorize speech and song, but this ability improves with age especially for identifying song. Despite generally rating song as more speech-like, 4- and 6-year-olds rated ambiguous speech-song stimuli as more song-like than 8-year-olds and adults. Four acoustic features predicted song ratings: F0 instability, utterance duration, harmonicity, and spectral flux. However, 4- and 6-year-olds' song ratings were better predicted by F0 instability than by harmonicity and utterance duration. These studies characterize how children develop conceptual and perceptual understandings of speech and song and suggest that children under age 8 are still learning what features are important for categorizing utterances as speech or song. RESEARCH HIGHLIGHTS: Children and adults conceptually and perceptually categorize speech and song from age 4. Listeners use F0 instability, harmonicity, spectral flux, and utterance duration to determine whether vocal stimuli sound like song. Acoustic cue weighting changes with age, becoming adult-like at age 8 for perceptual categorization and at age 12 for conceptual differentiation. Young children are still learning to categorize speech and song, which leaves open the possibility that music- and language-specific skills are not so domain-specific.

Fast rule switching and slow rule updating in a perceptual categorization task.

To adapt to a changing world, we must be able to switch between rules already learned and, at other times, learn rules anew. Often we must do both at the same time, switching between known rules while also constantly re-estimating them. Here, we show these two processes, rule switching and rule learning, rely on distinct but intertwined computations, namely fast inference and slower incremental learning. To this end, we studied how monkeys switched between three rules. Each rule was compositional, requiring the animal to discriminate one of two features of a stimulus and then respond with an associated eye movement along one of two different response axes. By modeling behavior, we found the animals learned the axis of response using fast inference (rule switching) while continuously re-estimating the stimulus-response associations within an axis (rule learning). Our results shed light on the computational interactions between rule switching and rule learning, and make testable neural predictions for these interactions.

Categorical perception of Mandarin tones in neurotypical adults with subclinical autistic traits

Early studies have revealed that categorical speech perception is impaired in individuals with autism spectrum disorders. However, it remains unclear whether categorical speech perception ability is associated with subclinical autistic traits in neurotypical populations. The current study sought to address this question by examining categorical perception of Mandarin tones (T1, high-level; T4, falling) in young adults. One hundred and thirty-one college students were recruited to participate in two classic categorical perception task, identification and discrimination, and to fill in the Autism-Spectrum Quotient (AQ; Baron-Cohen et al., 2001) for measuring subclinical autistic traits. The results showed that identification slope and categorical boundary width were not significantly correlated with the overall AQ score and the scores of the five subscales. However, between-category discrimination accuracy was significantly correlated with the social subscale score, indicating that individuals with less social skills have heightened between-category discrimination ability. Possible theoretical and practical implications of this association in subclinical populations are discussed. The current study adds to a better understanding of the associations between subclinical autistic traits and categorical speech perception in neurotypical individuals. [Work supported by the Humanities and Social Sciences Foundation of Ministry of Education of China 20YJCZH079.]

Active Role of Self-Sustained Neural Activity on Sensory Input Processing: A Minimal Theoretical Model.

A growing body of work has demonstrated the importance of ongoing oscillatory neural activity in sensory processing and the generation of sensorimotor behaviors. It has been shown, for several different brain areas, that sensory-evoked neural oscillations are generated from the modulation by sensory inputs of inherent self-sustained neural activity (SSA). This letter contributes to that strand of research by introducing a methodology to investigate how much of the sensory-evoked oscillatory activity is generated by SSA and how much is generated by sensory inputs within the context of sensorimotor behavior in a computational model. We develop an abstract model consisting of a network of three Kuramoto oscillators controlling the behavior of a simulated agent performing a categorical perception task. The effects of sensory inputs and SSAs on sensory-evoked oscillations are quantified by the cross product of velocity vectors in the phase space of the network under different conditions (disconnected without input, connected without input, and connected with input). We found that while the agent is carrying out the task, sensory-evoked activity is predominantly generated by SSA (93.10%) with much less influence from sensory inputs (6.90%). Furthermore, the influence of sensory inputs can be reduced by 10.4% (from 6.90% to 6.18%) with a decay in the agent's performance of only 2%. A dynamical analysis shows how sensory-evoked oscillations are generated from a dynamic coupling between the level of sensitivity of the network and the intensity of the input signals. This work may suggest interesting directions for neurophysiological experiments investigating how self-sustained neural activity influences sensory input processing, and ultimately affects behavior.

Multi-modal imaging of the auditory-larynx motor network for voicing perception

Voicing is one of the most important characteristics of phonetic speech sounds. Despite its importance, voicing perception mechanisms remain largely unknown. To explore auditory-motor networks associated with voicing perception, we firstly examined the brain regions that showed common activities for voicing production and perception using functional magnetic resonance imaging. Results indicated that the auditory and speech motor areas were activated with the operculum parietale 4 (OP4) during both voicing production and perception. Secondly, we used a magnetoencephalography and examined the dynamical functional connectivity of the auditory-motor networks during a perceptual categorization task of /da/-/ta/ continuum stimuli varying in voice onset time (VOT) from 0 to 40 ms in 10 ms steps. Significant functional connectivities from the auditory cortical regions to the larynx motor area via OP4 were observed only when perceiving the stimulus with VOT 30 ms. In addition, regional activity analysis showed that the neural representation of VOT in the auditory cortical regions was mostly correlated with categorical perception of voicing but did not reflect the perception of stimulus with VOT 30 ms. We suggest that the larynx motor area, which is considered to play a crucial role in voicing production, contributes to categorical perception of voicing by complementing the temporal processing in the auditory cortical regions.

Overnight changes to dual-memory processes reflected in speech-perceptual performance.

Adults' ability to attain and retain nonnative speech sound categories vary substantially among individuals. While we know that speech-perceptual skills play a role, we know less about how consolidation-related changes in acoustic-phonetic memory contribute to perceptual tasks. The goal of this investigation was to examine contributions of memory and perceptual skills to the perceptual performance on a trained nonnative speech contrast over two days. Twenty-one adult participants (ages 18-24) completed four different experiments. Three of these assessed learning and memory: visual statistical learning (implicit), visual object recognition (explicit), and nonnative (Hindi dental-retroflex) speech-sound training. Participants completed the learning tasks around 8 p.m., and performance was measured shortly after learning and again 12 hours later. On a separate day, participants completed a categorical perception task on a native (/a/-/e/) vowel continuum. Nonnative speech perception was associated with implicit learning performance when both were assessed shortly after learning, and associated with the retention of explicit memory when both were assessed after an overnight delay. Native speech-sounds were at least marginally associated with nonnative speech perception performance on both days, but with a stronger association observed with performance assessed on Day 2. These findings provide preliminary support for the interpretation that speech-sounds are encoded by at least two memory systems in parallel, but that perceptual performance may reflect acoustic-phonetic knowledge learned by different memory systems over time since exposure. Moreover, performance on speech perception tasks in both native and nonnative speech-sounds may rely on similar retrieval mechanisms for long-term storage of speech-sound information.

Individual differences in attractive and repulsive context effects on shape categorization

How we perceive a visual form not only depends on the currently presented shape, but also on the temporal context in which it is shown. Earlier research found both attractive and repulsive context effects in perception. Tendencies to see the current stimulus similar to how the previous stimulus was seen (i.e., hysteresis, attraction) co-exist with tendencies that repel the current percept away from the organization for which there was most evidence in the previous stimulus (i.e., adaptation, repulsion). While previous research focused on group-level effects of temporal context, this study investigated whether everyone shows effects of the previous percept and the previous stimulus in the expected direction, and whether possible individual differences in these attractive and repulsive temporal context effects are consistent. Participants (N=209) conducted a perceptual categorization task with two series of abstract morph figures as stimuli, for which average temporal context effects were identified before. A Bayesian multilevel logistic regression analysis on the current percept was conducted to get estimates for the size of the hysteresis and adaptation effect per participant. Results indicate that almost everyone showed an attractive effect of what was perceived in the previous trial, while a repulsive effect of the previously shown stimulus was less universal. The size of the individual hysteresis and adaptation effects were strongly correlated: participants with a more outspoken attractive effect of the previous percept also showed a stronger repulsive effect of the previous stimulus. Furthermore, individual differences in the strength of the adaptation effect were heavily correlated with individual differences in the sensitivity to perceptual differences between the different morph levels. The study provides evidence for different percepts in different individuals even when presented with the same stimulus in the same context and thereby increases insight in how different individuals differentially combine previous and current input in their perception.

Cognitive Flexibility for Semantic and Perceptual Information in Developmental Stuttering.

Purpose The purpose of this study was to examine cognitive flexibility for semantic and perceptual information in preschool children who stutter (CWS) and who do not stutter (CWNS). Method Participants were 44 CWS and 44 CWNS between the ages of 3;0 and 5;11 (years;months). Cognitive flexibility was measured using semantic and perceptual categorization tasks. In each task, children were required to match a target object with two different semantic or perceptual associates. Main dependent variables were reaction time and accuracy. Results The accuracy with which CWS and CWNS shifted between one semantic and perceptual representation to another was similar, but the CWS did so significantly more slowly. Both groups of children had more difficulty switching between perceptual representations than semantic ones. Conclusion CWS are less efficient (slower), though not less accurate, than CWNS in their ability to switch between different representations in both the verbal and nonverbal domains.

Perceptual errors are related to shifts in generalization of conditioned responding.

Studies of perceptual generalization have recently demonstrated a close relationship between stimulus perception and conditioned responding, suggesting that incorrect stimulus perception might account for certain characteristics of generalization gradients. In this study, we investigated whether common phenomena, such as the area and peak shift in conditioned responding, relate to perceptual errors. After a differential conditioning procedure, in which one circle was paired with the presentation of an aversive picture whereas a different-sized circle was not, we combined a generalization test with a three-alternative forced-choice perceptual categorization task where participants had to indicate on every trial whether the presented circle was one of the two circles from the conditioning phase or a different one, after which US-expectancy ratings were collected. The typical peak and area shift were observed when conditioned responses were plotted on a physical dimension. However, when stimulus perception was incorporated generalization gradients diverged from the typical gradient. Both the area and peak shift largely disappeared when accounting for perceptual errors. These findings demonstrate the need to incorporate perceptual mechanisms in associative models.

A difficulty predictor for perceptual category learning.

Predicting human performance in perceptual categorization tasks in which category membership is determined by similarity has been historically difficult. This article proposes a novel biologically motivated difficulty measure that can be generalized across stimulus types and category structures. The new measure is compared to 12 previously proposed measures on four extensive data sets that each included multiple conditions that varied in difficulty. The studies were highly diverse and included experiments with both continuous- and binary-valued stimulus dimensions, a variety of different stimulus types, and both linearly and nonlinearly separable categories. Across these four applications, the new measure was the most successful at predicting the observed rank ordering of conditions by difficulty, and it was also the most accurate at predicting the numerical values of the mean error rates in each condition.

Successful auditory motor adaptation requires task-relevant auditory errors.

When we produce speech movements, we also predict the auditory consequences of the movements. We use discrepancies between our predictions and incoming auditory information to modify our future movements (adapt). Although auditory errors are crucial for speech motor learning, not all perceived auditory errors are consequences of our own actions. Therefore, the brain needs to evaluate the relevance of perceived auditory errors. In this study, we examined error assessment processes involved in auditory motor adaptation by systematically manipulating the correspondence between speech motor outputs and their auditory consequences during speaking. Participants (n = 30) produced speech while they received perturbed auditory feedback (e.g., produced "head" but heard a word that sounded like "had"). In one condition, auditory errors were related to participants' productions (task-relevant errors). In another condition, auditory errors were defined by the experimenter and had no correspondence with participants' speech output (task-irrelevant errors). We found that the extent of adaptation and error sensitivity (derived from a state-space model) were greater in the condition with task-relevant auditory errors compared with those in the condition with task-irrelevant auditory errors. Additionally, participants with smaller perceptual targets (derived from a categorical perception task) adapted more to auditory perturbations, and participants with larger perceptual targets adapted less. Similarly, participants with smaller perceptual targets were more sensitive to errors in the condition with task-relevant auditory errors. Together, our results highlight the intricate mechanisms, involving both perception and production systems, that the brain uses to optimally integrate auditory errors for successful speech motor learning.NEW & NOTEWORTHY Feedback monitoring is essential for accurate speech production. By providing empirical results and a computational framework, we show that 1) the brain evaluates relevance of auditory errors and responds more to relevant errors, and 2) smaller perceptual targets are associated with more sensitivity to errors and more auditory motor adaptation.

Where Computation and Dynamics Meet: Heteroclinic Network-Based Controllers in Evolutionary Robotics.

In the fields of artificial neural networks and robotics, complicated, often high-dimensional systems can be designed using evolutionary/other algorithms to successfully solve very complex tasks. However, dynamical analysis of the underlying controller can often be near impossible, due to the high dimension and nonlinearities in the system. In this paper, we propose a more restricted form of controller, such that the underlying dynamical systems are forced to contain a dynamical object called a heteroclinic network. Systems containing heteroclinic networks share some properties with finite-state machines (FSMs) but are not discrete: both space and time are still described with continuous variables. Thus, we suggest that the heteroclinic networks can provide a hybrid between continuous and discrete systems. We investigate this innovated architecture in a minimal categorical perception task. The similarity of the controller to an FSM allows us to describe some of the system's behaviors as transition between states. However, other, essential behavior involves subtle ongoing interaction between the controller and the environment that eludes description at this level.