Category Boundaries Research Articles

Neuropsychology of Human Body Parts: Exploring Categorical Boundaries of Tactile Perception Using Somatosensory Mismatch Responses.

The focus of the current study is on a particular aspect of tactile perception: categorical segmentation on the body surface into discrete body parts. The MMN has been shown to be sensitive to categorical boundaries and language experience in the auditory modality. Here we recorded the somatosensory MMN (sMMN) using two tactile oddball protocols and compared sMMN amplitudes elicited by within- and across-boundary oddball pairs. Both protocols employed the identity MMN method that controls for responsivity at each body location. In the first protocol, we investigated the categorical segmentation of tactile space at the wrist by presenting pairs of tactile oddball stimuli across equal spatial distances, either across the wrist or within the forearm. Amplitude of the sMMN elicited by stimuli presented across the wrist boundary was significantly greater than for stimuli presented within the forearm, suggesting a categorical effect at an early stage of somatosensory processing. The second protocol was designed to investigate the generality of this MMN effect, and involved three digits on one hand. Amplitude of the sMMN elicited by a contrast of the third digit and the thumb was significantly larger than a contrast between the third and fifth digits, suggesting a functional boundary effect that may derive from the way that objects are typically grasped. These findings demonstrate that the sMMN is a useful index of processing of somatosensory spatial discrimination that can be used to study body part categories.

Efficient compression in color naming and its evolution

We derive a principled information-theoretic account of cross-language semantic variation. Specifically, we argue that languages efficiently compress ideas into words by optimizing the information bottleneck (IB) trade-off between the complexity and accuracy of the lexicon. We test this proposal in the domain of color naming and show that (i) color-naming systems across languages achieve near-optimal compression; (ii) small changes in a single trade-off parameter account to a large extent for observed cross-language variation; (iii) efficient IB color-naming systems exhibit soft rather than hard category boundaries and often leave large regions of color space inconsistently named, both of which phenomena are found empirically; and (iv) these IB systems evolve through a sequence of structural phase transitions, in a single process that captures key ideas associated with different accounts of color category evolution. These results suggest that a drive for information-theoretic efficiency may shape color-naming systems across languages. This principle is not specific to color, and so it may also apply to cross-language variation in other semantic domains.

Visual and Category Representations Shaped by the Interaction Between Inferior Temporal and Prefrontal Cortices

The ability to group items and events into functional categories is a fundamental function for visual recognition. Experimental studies have shown the different roles in information representations of inferior temporal (IT) and prefrontal cortices (PFC) in a categorization task. However, it remains elusive how category information is generated in PFC and maintained in a delay period and how the interaction between IT and PFC influences category performance. To address these issues, we develop a network model of visual system, which performs a delayed match-to-category task. The model consists of networks of V4, IT, and PFC. We show that in IT visual information required for categorization is represented by a combination of prototype features. We also show that category information in PFC is represented by two dynamical attractors weakly linked, resulting from the difference in firing thresholds of PFC neurons. Lower and higher firing thresholds contribute to working memory maintenance and decision-making, respectively. Furthermore, we show that top-down signal from PFC to IT improves the ability of PFC neurons to categorize the mixed images that are closer to a category boundary. Our model may provide a clue for understanding the neural mechanism underlying categorization task.

Effects of spectral resolution on spectral contrast effects in cochlear-implant users.

The identity of a speech sound can be affected by the long-term spectrum of a preceding stimulus. Poor spectral resolution of cochlear implants (CIs) may affect such context effects. Here, spectral contrast effects on a phoneme category boundary were investigated in CI users and normal-hearing (NH) listeners. Surprisingly, larger contrast effects were observed in CI users than in NH listeners, even when spectral resolution in NH listeners was limited via vocoder processing. The results may reflect a different weighting of spectral cues by CI users, based on poorer spectral resolution, which in turn may enhance some spectral contrast effects.

Moving towards a bilingual baseline in second language phonetic research

Abstract This investigation compared adult sequential bilinguals and native speakers (NSs) with the intention of determining if bilinguals are an appropriate comparison group for second language (L2) learners in L2 phonetic research. To that end, 16 Spanish-English bilinguals were compared to 20 NSs of English on their perception and production of two English vowels. In perception, both groups had a similar category boundary and acoustic cue weighting. In production, both groups produced distinct vowels that were highly intelligible, although the bilinguals produced the phonemes closer together in the vowel space and had more variable performance than the NSs. The inspection of these two participant groups reveals that bilinguals have the ability to perceive and produce a difficult L2 phonemic contrast, with slight and inconsequential differences when compared to NSs. Thus, I argue that bilinguals who have acquired a target structure are an apt comparison group in L2 phonetic experiments.

Proposed Imprecision Quality Goals for Urinary Albumin/Creatinine Ratio.

BackgroundThe urinary albumin/creatinine ratio (ACR) is an important indicator of albuminuria. We aimed to estimate ACR uncertainty and its impact on test results and proposed imprecision quality goals based on the estimated uncertainty.MethodsThe combined ACR uncertainty was calculated using the individual uncertainties of urinary albumin and creatinine. ACR confidence intervals (CIs) were estimated based on the expanded uncertainty. When the CI contained the ACR category boundary (30 or 300 mg/g), the cases were considered ambiguous. Quality goals for ACR were suggested using the number of ambiguous cases among actual patient results.ResultsThe number of ambiguous cases resulting from the combined ACR uncertainty was higher than expected based on biological variation (BV) quality goals. When the ACR met BV quality specifications, we estimated that 4.8–15.5% of the results may have been misclassified. To minimize the number of ambiguous results, the minimum, desirable, and optimum quality goals were set at 34.0%, 18.0%, and 4.5%, respectively.ConclusionsWe expressed ACR uncertainty using the uncertainties of urinary albumin and creatinine and assessed the impact of this combined uncertainty on the test results. Subsequently, we proposed imprecision quality goals for ACR based on ambiguous results.

Rapid visual perception of interracial crowds: Racial category learning from emotional segregation.

Drawing from research on social identity and ensemble coding, we theorize that crowd perception provides a powerful mechanism for social category learning. Crowds include allegiances that may be distinguished by visual cues to shared behavior and mental states, providing perceivers with direct information about social groups and thus a basis for learning social categories. Here, emotion expressions signaled group membership: to the extent that a crowd exhibited emotional segregation (i.e., was segregated into emotional subgroups), a visible characteristic (race) that incidentally distinguished emotional subgroups was expected to support categorical distinctions. Participants were randomly assigned to view interracial crowds in which emotion differences between (black vs. white) subgroups were either small (control condition) or large (emotional segregation condition). On each trial, participants saw crowds of 12 faces (6 black, 6 white) for roughly 300 ms and were asked to estimate the average emotion of the entire crowd. After all trials, participants completed a racial categorization task and self-report measure of race essentialism. As predicted, participants exposed to emotional segregation (vs. control) exhibited stronger racial category boundaries and stronger race essentialism. Furthermore, such effects accrued via ensemble coding, a visual mechanism that summarizes perceptual information: emotional segregation strengthened participants' racial category boundaries to the extent that segregation limited participants' abilities to integrate emotion across racial subgroups. Together with evidence that people observe emotional segregation in natural environments, these findings suggest that crowd perception mechanisms support racial category boundaries and race essentialism. (PsycINFO Database Record

The singleton-geminate distinction can be rate dependent: Evidence from Maltese

Many languages distinguish short and long consonants, or singletons and geminates. The primary acoustic correlate of this distinction is the duration of the consonants. Given that the absolute duration of speech sounds varies with speech rate, the question rises to what extent the category boundary between singletons and geminates is sensitive to the overall speech rate (i.e., rate normalization). Next to rate normalization, there are two other possible explanations how singletons and geminates might be distinguished. First, it has been suggested that despite variation in absolute duration, the two categories remain distinct; that is, even in fast speech, geminates seldom take on durations that would be typical of singletons at slow speech rates. Second, it has been suggested that, with higher speech rate, both the duration of consonants and vowels shrink, so that the duration ratio of consonant and adjacent vowel is a rate independent cue for the singleton-geminate distinction. Using production and perception data from Maltese, we show that, first, the singleton-geminate distinction is endangered by speech-rate variation and, second, consequently undergoes speech-rate normalization.

Training Humans to Categorize Monkey Calls: Auditory Feature- and Category-Selective Neural Tuning Changes

Grouping auditory stimuli into common categories is essential for a variety of auditory tasks, including speech recognition. We trained human participants to categorize auditory stimuli from a large novel set of morphed monkey vocalizations. Using fMRI-rapid adaptation (fMRI-RA) and multi-voxel pattern analysis (MVPA) techniques, we gained evidence that categorization training results in two distinct sets of changes: sharpened tuning to monkey call features (without explicit category representation) in left auditory cortex and category selectivity for different types of calls in lateral prefrontal cortex. In addition, the sharpness of neural selectivity in left auditory cortex, as estimated with both fMRI-RA and MVPA, predicted the steepness of the categorical boundary,whereas categorical judgment correlated with release from adaptation in the left inferior frontal gyrus. These results support the theory that auditory category learning follows a two-stage model analogous to the visual domain, suggesting general principles of perceptual category learning in the human brain.

Children’s Understanding of the Life Phenomenon for the Object in Category Boundaries

Children’s Understanding of the Life Phenomenon for the Object in Category Boundaries

Functions of collective victimhood

The conflict that played out in Northern Ireland between 1969 and 1998 is commonly referred to as the Troubles. Over the course of almost 30 years just under 3,700 people were killed and an estimated 40,000–80,000 injured; it is thought that 80% of the population of Northern Ireland knew someone who had been killed or injured in the violence. The protracted conflict that played out between local communities, the state and paramilitary organisations left a legacy of community division in the region; competing narratives of victimhood emerged and they served to inform intergroup relations. This article will provide a brief overview of the functions of collective victimhood as manifested in the social psychological literature, drawing on the example of the Troubles in Northern Ireland as a case study. In doing so, we will focus particularly on the mobilisation of collective victimhood as both a precursor for involvement in conflict but also as a justification after the event. Additionally, we are interested in the superordinate (broad societal level) re-categorisations of subgroups based on collective identities, including victimhood, and how they can be used as a conflict transformation resource. Ultimately, we will argue that research has tended to overlook how those involved in (as well as those impacted by) the Troubles construct and mobilise victimhood identities, for what purpose and to what end. We argue that in order to understand how collective victimhood is used and to understand the function it serves, both as a precursor for involvement in conflict and as a conflict transformation resource, we need to understand how parties to the conflict, both victims and perpetrators, construct the boundaries of these identity categories, as well as their rhetorical counterpart perpetrators of political violence.

Neural basis for categorical boundaries in the primate pre-SMA during relative categorization of time intervals

Perceptual categorization depends on the assignment of different stimuli to specific groups based, in principle, on the notion of flexible categorical boundaries. To determine the neural basis of categorical boundaries, we record the activity of pre-SMA neurons of monkeys executing an interval categorization task in which the limit between short and long categories changes between blocks of trials within a session. A large population of cells encodes this boundary by reaching a constant peak of activity close to the corresponding subjective limit. Notably, the time at which this peak is reached changes according to the categorical boundary of the current block, predicting the monkeys’ categorical decision on a trial-by-trial basis. In addition, pre-SMA cells also represent the category selected by the monkeys and the outcome of the decision. These results suggest that the pre-SMA adaptively encodes subjective duration boundaries between short and long durations and contains crucial neural information to categorize intervals and evaluate the outcome of such perceptual decisions.

Quantitative study of color category boundaries.

We use World Color Survey (WCS) data to design quantitative methods to study color categorization, with the focus on the "geometric" properties of categories, in particular, on studying their shape, and creating a consistent methodology to identify category boundaries. We introduce the notion of "No Man's Land" and "Some Man's Land" to distinguish color chips that belong to no color category and those that belong to some color category. We introduce a "color-stimulus-strength" function that characterizes color boundaries. While categories may come in a variety of shapes, and their boundaries are nonuniform and can vary in thickness, there are universal patterns that emerge. For example, the boundary-to-category-mass ratio is a decreasing function of category strength (i.e., stronger categories have relatively thinner boundaries), and boundary mass obeys a "square root"-like law as a function of category mass (i.e., roughly speaking, color categories behave like 2D circles). We further identify a relationship between color boundaries and Shannon's entropy, which can be calculated by using the field data of the WCS. We find that depending on the informational content of a given chip, it can belong to three distinct types: (I)strongly belonging to a color category; (II)belonging to a boundary between two or more categories; (III)not belonging to a category or a boundary. The last two cases can be interpreted in terms of evolution and temporal dynamics of color categories.

Music Communicates Affects, Not Basic Emotions - A Constructionist Account of Attribution of Emotional Meanings to Music.

Basic Emotion theory has had a tremendous influence on the affective sciences, including music psychology, where most researchers have assumed that music expressivity is constrained to a limited set of basic emotions. Several scholars suggested that these constrains to musical expressivity are explained by the existence of a shared acoustic code to the expression of emotions in music and speech prosody. In this article we advocate for a shift from this focus on basic emotions to a constructionist account. This approach proposes that the phenomenon of perception of emotions in music arises from the interaction of music’s ability to express core affects and the influence of top-down and contextual information in the listener’s mind. We start by reviewing the problems with the concept of Basic Emotions, and the inconsistent evidence that supports it. We also demonstrate how decades of developmental and cross-cultural research on music and emotional speech have failed to produce convincing findings to conclude that music expressivity is built upon a set of biologically pre-determined basic emotions. We then examine the cue-emotion consistencies between music and speech, and show how they support a parsimonious explanation, where musical expressivity is grounded on two dimensions of core affect (arousal and valence). Next, we explain how the fact that listeners reliably identify basic emotions in music does not arise from the existence of categorical boundaries in the stimuli, but from processes that facilitate categorical perception, such as using stereotyped stimuli and close-ended response formats, psychological processes of construction of mental prototypes, and contextual information. Finally, we outline our proposal of a constructionist account of perception of emotions in music, and spell out the ways in which this approach is able to make solve past conflicting findings. We conclude by providing explicit pointers about the methodological choices that will be vital to move beyond the popular Basic Emotion paradigm and start untangling the emergence of emotional experiences with music in the actual contexts in which they occur.

Co-production in community mental health services: blurred boundaries or a game of pretend?

The concept of co-production suggests a collaborative production of public welfare services, across boundaries of participant categories, for example professionals, service users, peer-workers and volunteers. While co-production has been embraced in most European countries, the way in which it is translated into everyday practice remains understudied. Drawing on ethnographic data from Danish community mental health services, we attempt to fill this gap by critically investigating how participants interact in an organisational set-up with blurred boundaries between participant categories. In particular, we clarify under what circumstances the blurred boundaries emerge as believable. Theoretically, we combine Lamont and Molnár's (2002) distinction between symbolic boundaries and social boundaries with Goffman's (1974) microanalysis of "principles of convincingness". The article presents three findings: (1) co-production is employed as a symbolic resource for blurring social boundaries; (2) the believability of blurred boundaries is worked up through participants' access to resources of validation, knowledge and authority; and (3) incongruence between symbolic and social boundaries institutionalises practices where participants merely act 'as if' boundaries are blurred. Clarification of the principles of convincingness contributes to a general discussion of how co-production frames the everyday negotiation of symbolic and social boundaries in public welfare services.

"It Was Not Me That Was Sick, It Was the Building": Rhetorical Identity Management Strategies in the Context of Observed or Suspected Indoor Air Problems in Workplaces.

Suffering from a contested illness poses a serious threat to one's identity. We analyzed the rhetorical identity management strategies respondents used when depicting their health problems and lives in the context of observed or suspected indoor air (IA) problems in the workplace. The data consisted of essays collected by the Finnish Literature Society. We used discourse-oriented methods to interpret a variety of language uses in the construction of identity strategies. Six strategies were identified: respondents described themselves as normal and good citizens with strong characters, and as IA sufferers who received acknowledge from others, offered positive meanings to their in-group, and demanded recognition. These identity strategies located on two continua: (a) individual- and collective-level strategies and (b) dissolved and emphasized (sub)category boundaries. The practical conclusion is that professionals should be aware of these complex coping strategies when aiming to interact effectively with people suffering from contested illnesses.

Illuminating ATOM: Taking time across the colour category border

Walsh's A Theory Of Magnitude (ATOM) contends that we represent magnitudes such as number, space, time and luminance on a shared metric, such that “more” of one leads to the perception of “more” of the other (e.g. Walsh, 2003). In support of ATOM, participants have been shown to judge intervals between stimuli that are more discrepant in luminance as having a longer duration than intervals between stimuli whose luminance differs by a smaller degree (Xuan, Zhang, He, & Chen, 2007). We tested the potential limits to the ability of luminance to influence duration perception by investigating the possibility that the luminance-duration relationship might be interrupted by a concurrent change in the colour of that luminance. We showed native Greek and native English speakers sequences of stimuli that could be either light or dark versions of green or blue. Whereas for both groups a shift in green luminance does not comprise a categorical shift in colour, for Greek speakers shifts between light and dark blue cross a colour category boundary (ghalazio and ble respectively). We found that duration judgements were neither interrupted nor inflated by a shift in colour category. These results represent the first evidence that the influence of luminance change on duration perception is resistant to interference from discrete changes within the same perceptual input.

Mechanisms underlying speech sound discrimination and categorization in humans and zebra finches

Speech sound categorization in birds seems in many ways comparable to that by humans, but it is unclear what mechanisms underlie such categorization. To examine this, we trained zebra finches and humans to discriminate two pairs of edited speech sounds that varied either along one dimension (vowel or speaker sex) or along two dimensions (vowel and speaker sex). Sounds could be memorized individually or categorized based on one dimension or by integrating or combining both dimensions. Once training was completed, we tested generalization to new speech sounds that were either more extreme, more ambiguous (i.e., close to the category boundary), or within-category intermediate between the trained sounds. Both humans and zebra finches learned the one-dimensional stimulus–response mappings faster than the two-dimensional mappings. Humans performed higher on the trained, extreme and within-category intermediate test-sounds than on the ambiguous ones. Some individual birds also did so, but most performed higher on the trained exemplars than on the extreme, within-category intermediate and ambiguous test-sounds. These results suggest that humans rely on rule learning to form categories and show poor performance when they cannot apply a rule. Birds rely mostly on exemplar-based memory with weak evidence for rule learning.

Lexical Retuning Targets Features

Previous work has shown that listeners systematically ``retune'' their categorical boundaries when presented with real-word tokens containing an ambiguous segment. There have been multiple previous studies on this lexically-guided retuning (Eisner and Mc- Queen 2005; McQueen et al. 2006; Norris et al. 2003), but the level of representation that retuning targets is not entirely clear. In this paper, we show that retuning occurs at the level of features for fricatives. Given that previous research has argued similarly for stops (Kraljic & Samuel 2006), we suggest that retuning generally targets featural representations.

Practising Ecumenism Through Boundary Work and Meta-Coding

Drawing on ethnographic fieldwork on religion in Zambia, this article engages critically with approaches that suggest that ecumenism necessarily occurs across socio-religious boundaries. I argue that the objective of ecumenism – namely, good-willed co-operation between religious practitioners who are otherwise separated from each other in terms of their institutional affiliations – can also be attained through boundary work and use of the meta-codes ‘non-Christian – Christian’ and ‘Christian –“real” Christian’. I contend that using these meta-codes in the logic of what has been called ‘fractal recursion’ allows people to stress situationally the existence of commonalities between religious practitioners and/or religious groupings that, at other points in time, are perceived to be different from each other. In this way, the shifting of categorical boundaries produces ecumenical reality effects.