Categorical invariance and structural complexity in human concept learning

An alternative account of human concept learning based on an invariance measure of the categorical stimulus is proposed. The categorical invariance model (CIM) characterizes the degree of structural complexity of a Boolean category as a function of its inherent degree of invariance and its cardinality or size. To do this we introduce a mathematical framework based on the notion of a Boolean differential operator on Boolean categories that generates the degrees of invariance (i.e., logical manifold) of the category in respect to its dimensions. Using this framework, we propose that the structural complexity of a Boolean category is indirectly proportional to its degree of categorical invariance and directly proportional to its cardinality or size. Consequently, complexity and invariance notions are formally unified to account for concept learning difficulty. Beyond developing the above unifying mathematical framework, the CIM is significant in that: (1) it precisely predicts the key learning difficulty ordering of the SHJ [Shepard, R. N., Hovland, C. L., & Jenkins, H. M. (1961). Learning and memorization of classifications. Psychological Monographs: General and Applied, 75(13), 1-42] Boolean category types consisting of three binary dimensions and four positive examples; (2) it is, in general, a good quantitative predictor of the degree of learning difficulty of a large class of categories (in particular, the 41 category types studied by Feldman [Feldman, J. (2000). Minimization of Boolean complexity in human concept learning. Nature, 407, 630-633]); (3) it is, in general, a good quantitative predictor of parity effects for this large class of categories; (4) it does all of the above without free parameters; and (5) it is cognitively plausible (e.g., cognitively tractable).     

Phonological Concept Learning

Linguistic and non‐linguistic pattern learning have been studied separately, but we argue for a comparative approach. Analogous inductive problems arise in phonological and visual pattern learning. Evidence from three experiments shows that human learners can solve them in analogous ways, and that human performance in both cases can be captured by the same models. We test GMECCS (Gradual Maximum Entropy with a Conjunctive Constraint Schema), an implementation of the Configural Cue Model (Gluck & Bower, 1988a ) in a Maximum Entropy phonotactic‐learning framework (Goldwater & Johnson, 2003 ; Hayes & Wilson, 2008 ) with a single free parameter, against the alternative hypothesis that learners seek featurally simple algebraic rules (“rule‐seeking”). We study the full typology of patterns introduced by Shepard, Hovland, and Jenkins ( 1961 ) (“SHJ”), instantiated as both phonotactic patterns and visual analogs, using unsupervised training. Unlike SHJ, Experiments 1 and 2 found that both phonotactic and visual patterns that depended on fewer features could be more difficult than those that depended on more features, as predicted by GMECCS but not by rule‐seeking. GMECCS also correctly predicted performance differences between stimulus subclasses within each pattern. A third experiment tried supervised training (which can facilitate rule‐seeking in visual learning) to elicit simple rule‐seeking phonotactic learning, but cue‐based behavior persisted. We conclude that similar cue‐based cognitive processes are available for phonological and visual concept learning, and hence that studying either kind of learning can lead to significant insights about the other.     

Dissociative states and neural complexity

Recent findings indicate that neural mechanisms of consciousness are related to integration of distributed neural assemblies. This neural integration is particularly vulnerable to past stressful experiences that can lead to disintegration and dissociation of consciousness. These findings suggest that dissociation could be described as a level of neural disintegration reflecting a number of independent processes by means of neural complexity. In the present study measurement of dissociation, traumatic stress symptoms and neural complexity calculated using nonlinear analysis of EEG [during rest conditions], and electrodermal activity (EDA) [during rest and Stroop task] were performed in 52 university students (mean age 24.1). Neural complexity has been described using pointwise correlation dimension (PD2) calculated from EEG and EDA records. While no significant relationship was found between EEG complexity and dissociative symptoms, statistically significant relationship between EDA complexity and dissociative symptoms during rest, but not during the Stroop task, has been found. These results indicate that electrodermal complexity during rest may reflect a level of dissociative symptoms.     

Criterion-related bias with the guide to the assessment of test-session behavior for the WISC-III and WIAT: Possible race/ethnicity, gender, and SES effects

Using the Guide to the Assessment of Test-Session Behavior for the WISC-III and WIAT (GATSB), Anglo examiners recorded test observations for 969 children between the ages of 6 and 16 years. The children came from the standardization and validity-study samples of GATSB ratings completed with the Wechsler Intelligence Scale-Third Edition (WISC-III) (Wechsler, 1991). The sample differed by race (Anglo, black, Latino), socioeconomic status (SES) (high, middle, low), and gender. GATSB ratings and WISC-III Verbal, Performance, and Full Scale IQs were compared. Correlations between the GATSB and WISC-III were generally moderate (average R = -.27). Children who exhibited higher levels of avoidance, inattentiveness, and uncooperative behaviors while being tested tended to exhibit lower WISC-III scores. This pattern held true for Anglos, blacks, and Latinos; for girls and boys; and for those from high-, middle-, and low-SES homes. Evidence was generally absent that Anglo examiners display bias in black-Anglo, gender, or SES comparisons. However, consistent differences were noted between Latino and Anglo children. Examiners tended to rate Latinos as displaying better test behaviors than Anglos when children's IQs were below average, but comparable when IQs were average and above. Thus, the GATSB generally displayed similar intrasession validities for children who differ by race/ethnicity, gender, and SES.     

Determining the bias and variance of a deterministic finger-tracking algorithm

Finger tracking has the potential to expand haptic research and applications, as eye tracking has done in vision research. In research applications, it is desirable to know the bias and variance associated with a finger-tracking method. However, assessing the bias and variance of a deterministic method is not straightforward. Multiple measurements of the same finger position data will not produce different results, implying zero variance. Here, we present a method of assessing deterministic finger-tracking variance and bias through comparison to a non-deterministic measure. A proof-of-concept is presented using a video-based finger-tracking algorithm developed for the specific purpose of tracking participant fingers during a psychological research study. The algorithm uses ridge detection on videos of the participant’s hand, and estimates the location of the right index fingertip. The algorithm was evaluated using data from four participants, who explored tactile maps using only their right index finger and all right-hand fingers. The algorithm identified the index fingertip in 99.78 % of one-finger video frames and 97.55 % of five-finger video frames. Although the algorithm produced slightly biased and more dispersed estimates relative to a human coder, these differences (x=0.08 cm, y=0.04 cm) and standard deviations (σ_x=0.16 cm, σ_y=0.21 cm) were small compared to the size of a fingertip (1.5–2.0 cm). Some example finger-tracking results are provided where corrections are made using the bias and variance estimates.     

Effects of visual and auditory guidance on bimanual coordination complexity

Perceptual guidance of movement with simple visual or temporal information can facilitate performance of difficult coordination patterns. Guidance may override coordination constraints that usually limit stability of bimanual coordination to only in-phase and anti-phase. Movement dynamics, however, might not have the same characteristics with and without perceptual guidance. Do visual and auditory guidance produce qualitatively different dynamical organization of movement? An anti-phase wrist flexion and extension coordination task was performed under no specific perceptual guidance, under temporal guidance with a metronome, and under visual guidance with a Lissajous plot. For the time series of amplitudes, periods and relative phases, temporal correlations were measured with Detrended Fluctuation Analysis and complexity levels were measured with multiscale entropy. Temporal correlations of amplitudes and relative phases deviated from the typical 1/f variation towards more random variation under visual guidance. The same was observed for the series of periods under temporal guidance. Complexity levels for all time series were lower in visual guidance, but higher for periods under temporal guidance. Perceptual simplification of the task’s goal may produce enhancement of performance, but it is accompanied by changes in the details of movement organization that may be relevant to explain dependence and poor retention after practice under guidance.     

Task bias and the accuracy of judgment: Setting a baseline for expected group performance

When a judgment task evokes unbiased estimates (i.e. the errors in individual judgments are distributed randomly around the true value), mathematical aggregation of individual estimates, even by a simple arithmetic mean, often will outperform all group members. However, when a task evokes biased estimates, mathematical aggregation does not perform so well. In this study, simulated data were accumulated to specify the expected' accuracy of mathematical aggregation relative to the accuracy of observed judgment of individual group members under varying conditions of task bias. Three types of judgment tasks were employed: (1) single-estimate, holistic tasks, (2) multiple-estimate, ranking tasks, and (3) multi-cue, decomposed tasks. Findings indicated across all task types that a large percentage of judgment-making group estimates formed strictly by computing the arithmetic mean of individual estimates performed better than their most capable members when a judgment task evoked little or no bias, a result particularly pronounced for ranking tasks. When the task was more greatly bias-evoking, a large percentage of parallel groups performed more poorly than average (or median) members, again a pattern more starkly evident for ranking tasks. These results suggest that the extent to which a judgment task evokes bias in a population of prospective group members is an important explanatory variable deserving much greater attention in the study of group performance. For example, an assertion about the efficacy of a particular group intervention based on a reliable demonstration of group performance as accurate as the most capable members may be unfounded when a task evokes no bias, since the baseline standard under such conditions should be much higher. By selecting tasks and populations that jointly produced highly biased estimates, researchers can lower the performance floor enough to detect (with reasonably small samples of groups) experimental effects should they occur.     

Categorization behaviour in adults,adolescents, and attention-deficit/hyperactivity disorder adolescents: A comparative investigation

Although significant progress has been made with respect to our understanding of categorization and concept learning behaviour in adults, much less is known about how this key capacity plays out with respect to more restrictive populations. This is unfortunate because much may be revealed about the nature of concept learning by examining the limits exhibited by special populations. With this tenet in mind, in what follows, we investigated key aspects of concept learning in terms of the unexplored comparative performance of three populations—adults, adolescents, and adolescents with attention-deficit/hyperactivity disorder (ADHD). To do so, we employed a novel parainformative experimental task involving categorical stimuli with four objects defined over three dimensions. The learning difficulty ordering for these types of three-dimensional stimuli has proven robust and has been replicated by several researchers. Indeed, in our experiment, we observed the same concept learning ordering in adults and adolescents, but not in ADHD adolescents: For example, the latter group showed greatly impaired categorization performance on stimuli characterized by an “exclusive-or” rule. However, categorization performance on such type of stimuli indicated good reliability in discriminating between adolescents with and without ADHD (receiver-operating characteristic, ROC?=?.82). We accurately predicted and accounted for these results using generalized invariance structure theory (GIST; Vigo, 2013. The GIST of concepts. Cognition, 129, 138–162), which posits that organisms detect invariance patterns in stimuli that are necessary precursors to concept formation.     

Stuttering, cluttering, and phonological complexity: case studies

The phonological complexity of dysfluencies in those who clutter and/or stutter may help us better understand phonetic factors in these two types of fluency disorders. In this preliminary investigation, cases were three 14-year-old males, diagnosed as a Stutterer, a Clutterer, and a Stutterer–Clutterer. Spontaneous speech samples were transcribed, coded for dysfluent words which were then matched to fluent words on grammatical class (i.e., function vs. content), number of syllables and word familiarity. An Index of Phonological Complexity was determined per word, and word frequency, density and phonological neighborhood frequency were derived from an online database. Results showed that compared to fluent words, dysfluent words were more phonologically complex and ‘sparser’, implying that they have fewer phonological neighbors or words in which a single phoneme is added, deleted or substituted. Interpretations and future directions for research regarding phonological complexity in stuttering and cluttering are offered.Educational objectives: 1. The reader can list three key symptoms of cluttering. 2. The reader will define phonological neighborhood density and neighborhood frequency. 3. The reader can calculate the Index of Phonological Complexity (IPC) for a given word. 4. The reader can state two findings from the current study and how each relates to other studies of phonological complexity and fluency disorders.     

Integration of weight and distance information in young children: The role of relational complexity

Young children's integration of weight and distance information was examined using a new methodology that combines a single-armed apparatus with functional measurement. Weight and distance values were varied factorially across the item set. Children estimated how far the beam would tilt when different numbers of weights were placed at different distances from the pivot. There was a developmental progression from non-systematic responding (3-year-olds) to responding based on a single variable, usually weight (4-year-olds) to responding based on integration of weight and distance (5-, 6- and 7-year-olds). Individual analyses revealed additive and multiplicative integration rules in children aged from 5 years. Weight–distance strategy complexity increased with age and was associated with better performance on independent measures of relational processing, especially the more complex items. Thus weight–distance integration involves processing of complex relational information. The findings enhance the explanatory power of Relational Complexity theory as a domain-general approach to cognitive development.     

On the mean and variance of response times under the diffusion model with an application to parameter estimation

We give closed form expressions for the mean and variance of RTs for Ratcliff’s diffusion model [Ratcliff, R. (1978). A theory of memory retrieval. Psychological Review, 85, 59-108] under the simplifying assumption that there is no variability across trials in the parameters. These expressions are more general than those currently available. As an application, we demonstrate their use in a method-of-moments estimation procedure that addresses some of the weaknesses of the EZ method [Wagenmakers, E.-J., van der Maas, H. L. J., & Grasman, R. P. P. P. (2007). An EZ-diffusion model for response time and accuracy. Psychonomic Bulletin & Review, 14, 3-22], and illustrate this with lexical decision data. We discuss further possible applications.     

ANOVA and the variance homogeneity assumption: Exploring a better gatekeeper

Valid use of the traditional independent samples ANOVA procedure requires that the population variances are equal. Previous research has investigated whether variance homogeneity tests, such as Levene's test, are satisfactory as gatekeepers for identifying when to use or not to use the ANOVA procedure. This research focuses on a novel homogeneity of variance test that incorporates an equivalence testing approach. Instead of testing the null hypothesis that the variances are equal against an alternative hypothesis that the variances are not equal, the equivalence-based test evaluates the null hypothesis that the difference in the variances falls outside or on the border of a predetermined interval against an alternative hypothesis that the difference in the variances falls within the predetermined interval. Thus, with the equivalence-based procedure, the alternative hypothesis is aligned with the research hypothesis (variance equality). A simulation study demonstrated that the equivalence-based test of population variance homogeneity is a better gatekeeper for the ANOVA than traditional homogeneity of variance tests.     

The effect of stopping before turning on the direct observational measure of whole body turning bias

Turning bias, the preferential tendency to turn toward a given direction has been reported in both rodents and human participants. The observational gait method of determining turning bias in humans requires a stop prior to turning. This study removed the stop and hypothesised that turning bias would remain the same between stop and non-stop conditions if bias was solely under the control of neurochemical asymmetries. The results showed that statistically turning bias remained the same (to the left) regardless of method used but there was no agreement between the methods thus rejecting the hypothesis. It is likely that when not stopping biomechanical factors related to gait when turning influence the direction of turn rather than solely neurochemical asymmetries.     

Artifact, bias, and complexity of assessment: the ABCs of reliability

Interobserver agreement (also referred to here as "reliability") is influenced by diverse sources of artifact, bias, and complexity of the assessment procedures. The literature on reliability assessment frequently has focused on the different methods of computing reliability and the circumstances under which these methods are appropriate. Yet, the credence accorded estimates of interobserver agreement, computed by any method, presupposes eliminating sources of bias that can spuriously affect agreement. The present paper reviews evidence pertaining to various sources of artifact and bias, as well as characteristics of assessment that influence interpretation of interobserver agreement. These include reactivity of reliability assessment, observer drift, complexity of response codes and behavioral observations, observer expectancies and feedback, and others. Recommendations are provided for eliminating or minimizing the influence of these factors from interobserver agreement.     

Gender variance in children and adolescents with autism spectrum disorder from the National Database for Autism Research

Previous studies suggest elevated rates of gender variance (GV), the wish to be of the other gender, in those with autism spectrum disorder (ASD). This study aimed to understand the rate of GV in children and adolescents with ASD and explore differences in sex, age, and emotional-behavioral problems relative to those referred to clinical services for mental health concerns (“referred”) and to the general population (“non-referred”). A secondary analysis of data from the National Database for Autism Research was used to explore GV using a child behavior checklist, parent report, in 176 children aged 6 to 18 year with ASD compared to referred and non-referred cohorts. GV was present in 4.0% of the ASD group, higher than for the non-referred group (0.7%) but similar to the referred group (4.0%). There were no significant sex differences in GV prevalence (males 3.7%, females 6.0%) in the ASD group. That the GV rate was elevated in ASD relative to non-referred samples but similar to clinically referred samples suggests that elevated rates of GV were not specific to ASD and may be more broadly associated with neurodevelopmental and psychiatric disorders of childhood. Further population-based research using clinical assessment for gender dysphoria is required in individuals with ASD and other neurodevelopmental disorders.     

When two wrongs can make a right: Regulatory nonfit, bias, and correction of judgments

We propose that when people consider whether their judgments are accurate enough, feelings of wrongness from regulatory nonfit (inconsistency between regulatory state and strategic means) can suggest that the answer is no and enhance correction of judgments relative to feelings of rightness from regulatory fit. Results from two experiments supported that hypothesis. When we activated an accuracy motive, participants who experienced regulatory nonfit provided judgments more consistent with correction for bias when they experienced regulatory nonfit than when they experienced regulatory fit (Experiment 1). Drawing participants’ attention to an earlier event as a source of rightness feelings eliminated the effect of regulatory fit on apparent correction of judgments (Experiment 2), suggesting attribution of regulatory fit/nonfit feelings to the accuracy of those judgments.     

Perfectionism and efficiency: Accuracy,response bias,and invested time in proof-reading performance

Investigating problem-solving performance, Ishida, H. (2005). College students’ perfectionism and task-strategy inefficience: Why their efforts go unrewarded? Japanese Journal of Social Psychology, 20, 208–215. Found high levels of perfectionism were associated with lower efficiency. Aiming to replicate and further explore this finding, the present study investigated how two dimensions of perfectionism (high standards, discrepancy between expectations and performance) predicted efficiency in proof-reading performance. N = 96 students completed a proof-reading task involving the detection of spelling, grammar, and format errors. When error-detection performance was subjected to signal detection analysis, high standards correlated positively with the number of incorrectly detected errors (false alarms). Moreover, when task-completion time was taken into account, high standards were negatively correlated with efficiency (accuracy/time). In comparison, discrepancy correlated negatively with the number of correctly detected errors (hits) and positively with a conservative response bias. The findings show that perfectionistic standards are associated with reduced efficiency demonstrating the importance of considering invested time, errors, and response bias when investigating the relationship between perfectionism and performance.