Categorization Reaction Times Research Articles

Gene-Environment Interactions in Face Categorization: Oxytocin Receptor Genotype x Childcare Experience Shortens Reaction Time.

Human faces capture attention, provide information about group belonging, and elicit automatic prepared responses. Early experiences with other-race faces play a critical role in acquiring face expertise, but the exact mechanism through which early experience exerts its influence is still to be elucidated. Genetic factors and a multi-ethnic context are likely involved, but their specific influences have not been explored. This study investigated how oxytocin receptor gene (OXTR) genotypes and childcare experience interacted to regulate face categorization in adults. Information about single nucleotide polymorphisms of OXTR (rs53576) and experiences with own- and other-race child caregivers was collected from 89 Singaporean adults, who completed a visual categorization task with own- versus other-race faces. Participants were grouped into A/A homozygotes and G carriers and assigned a score to account for their type of child caregiver experience. A multivariate linear regression model was used to estimate the effect of genetic group, child caregiver experience, and their interaction on categorization reaction time. A significant interaction of genetic group and child caregiver experience (t = 2.48, p = 0.015), as well as main effects of both genetic group (t = −2.17, p = 0.033) and child caregiver experience (t = −4.29, p < 0.001) emerged. Post-hoc analysis revealed that the correlation between categorization reaction time and child caregiver experience was significantly different between the two genetic groups. A significant gene x environment interaction on face categorization appears to represent an indirect pathway through which genes and experiences interact to shape mature social sensitivity to faces in human adults.

A Meta-analysis of the Uncanny Valley's Independent and Dependent Variables

The uncanny valley (UV) effect is a negative affective reaction to human-looking artificial entities. It hinders comfortable, trust-based interactions with android robots and virtual characters. Despite extensive research, a consensus has not formed on its theoretical basis or methodologies. We conducted a meta-analysis to assess operationalizations of human likeness (independent variable) and the UV effect (dependent variable). Of 468 studies, 72 met the inclusion criteria. These studies employed 10 different stimulus creation techniques, 39 affect measures, and 14 indirect measures. Based on 247 effect sizes, a three-level meta-analysis model revealed the UV effect had a large effect size, Hedges’ g = 1.01 [0.80, 1.22]. A mixed-effects meta-regression model with creation technique as the moderator variable revealed face distortion produced the largest effect size, g = 1.46 [0.69, 2.24], followed by distinct entities, g = 1.20 [1.02, 1.38], realism render, g = 0.99 [0.62, 1.36], and morphing, g = 0.94 [0.64, 1.24]. Affective indices producing the largest effects were threatening, likable, aesthetics, familiarity , and eeriness , and indirect measures were dislike frequency, categorization reaction time, like frequency, avoidance , and viewing duration . This meta-analysis—the first on the UV effect—provides a methodological foundation and design principles for future research.

Reaction times predict dynamic brain representations measured with MEG for only some object categorisation tasks

Behavioural categorisation reaction times (RTs) provide a useful way to link behaviour to brain representations measured with neuroimaging. In this framework, objects are assumed to be represented in a multidimensional activation space, with the distances between object representations indicating their degree of neural similarity. Faster RTs have been reported to correlate with greater distances from a classification decision boundary for animacy. Objects inherently belong to more than one category, yet it is not known whether the RT-distance relationship, and its evolution over the time-course of the neural response, is similar across different categories. Here we used magnetoencephalography (MEG) to address this question. Our stimuli included typically animate and inanimate objects, as well as more ambiguous examples (i.e., robots and toys). We conducted four semantic categorisation tasks on the same stimulus set assessing animacy, living, moving, and human-similarity concepts, and linked the categorisation RTs to MEG time-series decoding data. Our results show a sustained RT-distance relationship throughout the time course of object processing for not only animacy, but also categorisation according to human-similarity. Interestingly, this sustained RT-distance relationship was not observed for the living and moving category organisations, despite comparable classification accuracy of the MEG data across all four category organisations. Our findings show that behavioural RTs predict representational distance for an organisational principle other than animacy, however further research is needed to determine why this relationship is observed only for some category organisations and not others.

Procedural learning of semantic categorization in Parkinson's disease.

This paper studies the procedural learning of semantic categorization in 29 patients with non-demented Parkinson's disease (PD). We investigated whether the PD group was able to develop semantic skill, using a cognitive procedural task developed in our laboratory, applying a manual and serial reaction time paradigm to semantic categorization. The PD group showed similar scores to those of the control group on semantic categorization. Both groups showed reaction time reduction over the semantic procedural task, but the PD group produced longer reaction times than the control subjects. Contrary to our prediction, we observed an improvement in semantic categorization reaction times with practice, even with new verbal material for the PD patients to categorize despite their motor impairments and executive deficits. By contrast, we found a significant negative correlation between axial motor signs and the ratio of semantic procedural learning, but not for lateral motor signs. The present results support the notion that non-demented PD patients may be capable of acquiring comparable semantic skill to those of the control group.

The dynamics of pattern identification and categorization

Whether identification and categorization of visual stimuli are supported by separate or identical neural circuits remains a matter of debate. Similarly, the dynamics of these processes are poorly understood: Does identification precede categorization, or vice-versa? To answer these questions, we measured how fast visual patterns are identified and categorized. In our identification task, subjects were initially trained to recognize a given pattern. In subsequent sessions, they had to indicate whether each of a series of patterns was identical to the learned pattern or not. In the categorization task, subjects trained with similar patterns defining an arbitrary category. They then had to indicate whether subsequently presented patterns belonged to the category or not. We measured accuracy and reaction times in both tasks. Performance improved during the first 3 to 4 sessions, then stabilized. While accuracy in both tasks showed similar dynamics with practice, the reaction times behaved differently: In the first session, the average reaction time for categorization was 716±193 ms, and 550±78 ms for identification. With training, categorization reaction times decreased more rapidly than in the identification task. Both types of reaction times then converged around 467 ms (500±81 ms categorization; 434±24 ms recognition). These results suggest that identification and categorization are two independent processes.

Procedural learning of semantic categorization: A study of 110 non-disabled individuals

Purpose. This paper describes a cognitive procedural task in order to study procedural learning of semantic categorization. We evaluated age, educational level and gender effects on semantic procedural skill.Methods. The procedural task was developed in our laboratory, applying a manual and serial reaction time paradigm to semantic categorization. We investigated this form of procedural learning in 110 non-disabled subjects.Results. We observed an improvement of semantic categorization reaction times (RTs) over time from practice, even with new verbal material to categorize. Age, educational level and gender did not influence procedural learning of semantic categorization but women performed faster than men.Conclusion. The results suggest that semantic categorization is susceptible to procedural training.

Effects of frequency on visual word recognition tasks: Where are they?

Compared the effect of frequency on lexical decision time (LDT) with that on reaction time (RT) in four other tasks, for the same words and subjects. Exp. 1 yielded an effect on semantic categorization RT (person vs. thing) similar in size and form to the effect on LDT. Exp. 2 yielded a substantial effect for syntactic categorization (noun vs. adjective), although weaker than the effect on LDT. In Exp. 3, the effect on naming RT for stress-final disyllabic words was identical to that on LDT, whereas the effect for stress-initial words was weaker. Exp. 4 showed no effect of frequency on delayed naming RT. The data undermine recent arguments for a (mainly) postidentification task-specific locus of frequency effects but are compatible with the older assumption (also characteristic of new PDP learning models) that lexical identification is a major locus of frequency effects (perhaps together with retrieval of meaning or phonology). But effects at that locus may be masked or diluted by other processes.

Categorization reaction time, category structure, and category size in semantic memory using artificial categories.

This study examined the effects of category structure and category size on categorization reaction time, artificial categories being used to obtain greater experimental control than is usually found in semantic memory research. Four artificial categories varying in structure (hierarchical and nonhierarchical) and size (8 or 16 instances) were introduced to 20 adolescent subjects over a 12-week period by means of stories, exercises, and discussions. Significantly longer categorization reaction times were required for instances from the hierarchical categories, but no set size effect was found. The application of clustering and multidimensional scaling procedures to subjects’ free recall data revealed that subjects had acquired the hierarchical structures but imposed their own structures on the other categories. These findings were interpreted within a spreading activation framework.

Identification and categorization in visual search

Seven experiments were addressed to the general question of whether the identification of letters and numbers is a more rapid process than the categorization of such stimuli. Subjects were required to make a single response if a target stimulus specified by name (e.g., "A," "2") or designated by category class alone (e.g., "letter," "number") was presented in a trial. The principal findings were: (1) identification reaction times (RTs) were faster than categorization RTs: (2) RTs for targets shown without a context were faster than RTs for targets shown in the context of other stimuli; (3) identification RTs for targets shown in the context of stimuli from a different conceptual-taxonomic category were faster than RTs for targets shown in the context of stimuli from the same category only when target-context stimulus discriminability differencet were optimized. The results were interpreted in terms of a two-stage processing model in which context face,ors affect the duration of an initial encoding-scanning stage and search instruction (effective memory size) factors affect the duration of the memory comparison stage.