What makes a categorization task difficult?

To understand why some categorization tasks are more difficult than others, we consider five factors that may affect human performance--namely, covariance complexity, optimal accuracy level with and without internal noise, orientation of the optimal categorization rule, and class separability. We argue that covariance complexity, an information-theoretic measure of complexity, is an excellent predictor of task difficulty. We present an experiment that consists of five conditions using a simulated medical decision-making task In the task human observers view hundreds of hypothetical patient profiles and classify each profile into Disease Category A or B. Each profile is a continuous-valued, three-dimensional stimulus consisting of three vertical bars, where each bar height represents the result of a medical test. Across the five conditions, covariance complexity was systematically manipulated. Results indicate that variation in performance is largely a function of covariance complexity and partly a function of internal noise. The remaining three factors do not explain performance results. We present a challenge to categorization theorists to design models that account for human performance as predicted by covariance complexity.     

How is performance limited: Testing the notion of central capacity

Two-dimensional pursuit tracking task was employed in three experiments designed to test three predictions of the central capacity model of performance limitations under time-sharing conditions. These are the predicted effects of change in task difficulty, task emphasis and their interaction. Each of simultaneously performed tracking dimensions (horizontal and vertical) was treated as a separate task and manipulated independently. Tracking difficulty on each dimension and their relative emphasis were jointly manipulated. When frequency or velocity of target movement served as difficulty parameters, and control complexity was relatively low, tradeoffs between dimensions in different priority conditions were small and task difficulty had no effect on the performance of the concurrent task, neither did it interact with task emphasis. When control complexity was increased and in addition was manipulated as the difficulty parameter, linear tradeoff was observed and difficulty seemed to interact with task emphasis. These results cannot be easily accommodated within a strict central capacity model. An alternative interpretation based on a multiple capacity approach is outlined.     

The Role of Subjective Task Complexity in Goal Orientation,Self-Efficacy,and Performance Relations

We examined the role of subjective task complexity in goal orientation effects on self-efficacy and performance on a computerized simulation of a class scheduling task (N = 138). Results indicated that goal orientation effects on performance were mediated by subjective task complexity. In addition, our results revealed that subjective task complexity was related to self-efficacy but not cognitive ability. Moreover, subjective task complexity effects on performance were mediated by self-efficacy, and goal orientation effects on self-efficacy were mediated by subjective task complexity. Results are discussed in terms of conceptual relations between goal orientation, subjective task complexity, self-efficacy, and performance.     

Maintenance of grip-induced muscle tension: a behavioral marker of schizophrenia.

A grip-induced muscle tension maintenance task distinguished between schizophrenic patients, regardless of medication or hospitalization status, and both normals and controls with affective (unipolar and bipolar) disorders. Unaffected first-degree relatives of schizophrenic patients also showed a grip deficit. Coupling the grip task with a visual discrimination task that divided attention through instruction or reinforcement contingency, increased grip error times for all groups. No group differences appeared on the discrimination task, regardless of difficulty level, and the tone used to provide corrective feedback was not implicated in the grip deficit. The results suggest that the grip task is tapping, in a systematic and reliable manner, a motor-control abnormality that may be useful as a behavioral marker of schizophrenia.     

Acquisition and transfer of conceptual learning by normals and retardates: the effects of modeling, verbal cues, and reinforcement

The present study compared the effects of modeling, verbal cues, and reinforcement on conceptual learning of normals and retardates. Performance on both original learning tasks and a transfer task was examined. The results indicated that, relative to a control group, modeling alone, modeling plus verbal cues, and exposure to the completed task plus verbal cues facilitated original conceptual learning. Furthermore, modeling plus verbal cues was more effective in reducing errors than modeling alone. Original learning was not affected by tangible reinforcement, social reinforcement, or IQ level. No significant effects were found for a transfer task.     

Phonological awareness and spelling in normal children and dyslexics: the case of initial consonant clusters

We investigated phonological awareness and spelling skills among normal readers and spellers in Grades 1 and 2 and among dyslexics who scored at the same level as the normals on a standardized spelling test. Both normal children and dyslexics had difficulty with consonants in word-initial clusters in a phoneme recognition task and a phoneme deletion task. Also, both groups of children had trouble producing legal spellings of syllables with initial clusters, sometimes failing to represent the second consonants of the clusters. The dyslexics' phonological awareness and spelling skills were poorer than those of the younger normal children, but the two groups showed similar patterns of performance.     

Goal Setting Effects on Implicit and Explicit Learning of Complex Tasks

The robust finding that setting difficult, specific goals leads to increased performance on simple tasks has not generalized to complex task performance. The results of the present research suggest that the moderating effect of task complexity on the goal–performance relationship is due to confounding goal difficulty with explicit and implicit learning. Two multiple cue probability learning studies were performed keeping the learning mode constant while varying goal difficulty. Study 1 examined goal setting effects on performance when task processing was implicit. Consistent with previous research on complex tasks, setting difficult, specific goals did not result in performance gains. Study 2 demonstrated that when complex task processing is explicit, goal setting results in gradual but steady improvements in complex task performance. Protocol analysis of strategies used by participants indicate that goal setting resulted in increased performance through the development of better strategies.     

Comparison of schizophrenics and normals on a visual search task.

The response times of 16 paranoids, 16 nonparanoids and 16 normals were compared on a search task which required subjects to identify target letters embedded in displays of varying numbers of non-targets. The rate on increase in response times with increased numbers of letters displayed was not markedly different for the various groups, although a derived measure of decision and response-selection time indicated that normals selected responses more rapidly. When compared with normals, schizophrenics seemed to experience more difficulty in response selection and decision than in processing visual stimulus information.     

Anxiety and Performance: The Processing Efficiency Theory

Abstract

Anxiety often impairs performance of “difficult” tasks (especially under test conditions), but there are numerous exceptions. Theories of anxiety and performance need to address at least two major issues: (1) the complexity and apparent inconsistency of the findings; and (2) the conceptual definition of task difficulty. Some theorists (e.g. Humphreys & Revelle, 1984; Sarason, 1988) argue that anxiety causes worry, and worry always impairs performance on tasks with high attentional or short-term memory demands. According to the processing efficiency theory, worry has two main effects: (1) a reduction in the storage and processing capacity of the working memory system available for a concurrent task; and (2) an increment in on-task effort and activities designed to improve performance. There is a crucial distinction within the theory between performance effectiveness (= quality of performance) and processing efficiency (= performance effectiveness divided by effort). Anxiety characteristically impairs efficiency more than effectiveness.     

Early conceptual and linguistic processes operate in independent channels

Language and concepts are intimately linked, but how do they interact? In the study reported here, we probed the relation between conceptual and linguistic processing at the earliest processing stages. We presented observers with sequences of visual scenes lasting 200 or 250 ms per picture. Results showed that observers understood and remembered the scenes' abstract gist and, therefore, their conceptual meaning. However, observers remembered the scenes at least as well when they simultaneously performed a linguistic secondary task (i.e., reading and retaining sentences); in contrast, a nonlinguistic secondary task (equated for difficulty with the linguistic task) impaired scene recognition. Further, encoding scenes interfered with performance on the nonlinguistic task and vice versa, but scene processing and performing the linguistic task did not affect each other. At the earliest stages of conceptual processing, the extraction of meaning from visually presented linguistic stimuli and the extraction of conceptual information from the world take place in remarkably independent channels.     

Development of hierarchical conceptual relationships in children's semantic memories

The present study was designed to determine when children first display evidence of hierarchical conceptual organization. Children aged 5 to 9 answered either semantic or sensory questions about a list of words composed of either superordinate terms, prototypical category instance, or moderately typical instances. In a later unanticipated cued recall task the children were given taxonomically related cues composed of the two remaining word types not used in the orienting phase. The 5-year-olds' performance revealed that they possessed a modest degree of hierarchically organized conceptual information, which by age 9 had developed to relatively sophisticated levels. In particular, it was found that the range of information contained in the 5-year-olds' conceptual hierarchies was considerably narrower than that of the 9-year-olds', which supports Rosch's contention that conceptual categories are first constructed around prototypical instances. The children's performance on the cued recall task was also compared to their performance on traditional class inclusion and object-sorting tasks. It was found that the object-sorting task overestimated, while the class inclusion task underestimated the extent to which conceptual information is hierarchically organized in 5-year-olds.     

Autonomic physiological activity in mental rotation tasks

The electrodermal response (EDR) during a mental rotation (MR) task performance was investigated. For 6 males and 8 females (16-25 years old) there was a progressive increase in the number of EDRs as the angle of rotation (complexity) of the task was increased. These results support previous findings that autonomic physiological activity varies with the amount of information processing or its difficulty.     

Sentence comprehension in Parkinson's disease: the role of attention and memory.

Sentence comprehension is a complex process involving at least attentional, memory, grammatical, and semantic components. We report three experiments designed to evaluate the impairments underlying sentence comprehension difficulties in nondemented patients with Parkinson's disease (PD). In the first experiment, we asked patients to answer simple questions about sentences which varied in terms of grammatical complexity and semantic constraint. We found that PD patients are significantly compromised in their ability to perform this task. Their difficulties became more prominent as grammatical complexity increased, but they were significantly assisted by semantic constraints that limited possible interpretations of a sentence. Analyses of individual patient profiles revealed heterogeneous performance across the group of PD patients and somewhat inconsistent performance for patients across testing sessions. In the second experiment, we tested the possibility that patients' heterogeneous performance on the sentence comprehension task is due to an impairment in memory or attention, cognitive domains known to be compromised in some PD patients. Although PD patients and control subjects differed on one memory measure, there were no significant correlations between attention and memory performance and the results of the sentence comprehension task. In the final experiment, we manipulated the sentences used in the first experiment in a fashion that stressed the need for memory and attention in a sentence. The results indicated that PD patients are significantly compromised in their ability to attend to certain critical grammatical features of a sentence. A regression analysis identified specific grammatical, semantic, and attentional mechanisms as significant contributors to PD patients' overall sentence comprehension, accounting for over 97% of the variance in their performance. We conclude that there are multiple sources of cognitive difficulty underlying PD patients' sentence comprehension impairment.     

Variables for designing cube folding tasks influencing sixth-graders' performance

This study investigated whether the three variables of task form, squares carried, and figural complexity, for designing cube folding tasks, affect sixth graders' cube folding performance. Two task forms were used to develop two versions of “cube folding test.” Each version was designed based on two levels of squares carried and three levels of figural complexity, and contained 18 multiple-choice items. The sample included 107 boys and 92 girls with an average age of 12.04 years who were randomly assigned to complete one of the two versions. A linear mixed model was carried out with three factors: task forms, squares carried, and figural complexity, in which squares carried and figural complexity were “within-subjects” factors, and task form was the “between-subjects” factor. The results showed the interaction effect of squares carried and task form, and the main effect of figural complexity, which differentiated the difficulty in cube folding tasks.     

Identifying the task characteristics that predict children's construction task performance

Construction tasks form a major part of children's play and can be linked to achievement in maths and science. However there is a lack of understanding of construction task ability and development. Therefore, there is little foundation for the applied use of construction tasks, such as in teaching or research, as there are no apparent methods for assessing difficulty. This empirical research identifies four construction task characteristics that impact on cognition and predict construction task difficulty in children aged 7–8 and 10–11 years and adults. The results also reveal a developmental trajectory in construction ability. The research provides a method to quantify, predict and control the complexity of construction tasks for future research and to inform applied use. Copyright © 2010 John Wiley & Sons, Ltd.     

Developmental trends in the use of perceptual and conceptual attributes in grouping,clustering, and retrieval

In Experiment I, two tasks were administered to children aged 4, 5, and 9 in order to investigate preference for perceptual versus conceptual attributes in grouping of common objects, and in various aspects of memory. The grouping task revealed a clear chronological progression: color and form determined the youngest children's grouping about equally; form dominated in the 5-year-olds; and most of the oldest children grouped primarily by conceptual attributes. In the memory task, three lists—one organized by color, one by form, one by superordinate category—were presented for free, followed by cued recall. Clustering showed the developmental shift from color to form to concept, while cued recall showed conceptual superiority at all ages. Experiment II replicated the memory task, yielding the same results. The results were discussed in terms of the relative abstractness and predictability of conceptual versus perceptual attributes and the difficulty of abstraction in encoding and the function of predictability in retrieval.     

平衡秤任务复杂性的事前与事后分析

任务复杂性的分析和评估是心理测量学和认知心理学都非常关注的重要主题。以264名小学四、五、六年级儿童为被试,平衡秤任务为研究材料,考察任务在未旋转时第一个因素上的载荷(事后分析)能否作为评价任务复杂性的一个指标,以及关系-表征复杂性模型对平衡秤任务复杂性分析(事前分析)的有效性两个问题。结果表明:平衡秤任务施测后所得所有项目的因素载荷与其难度之间没有显著正相关,即因素载荷的高低没有反映平衡秤任务复杂性的大小;而基于关系-表征复杂性模型对任务的事前分析所确定的任务等级复杂性和知识经验对任务难度的解释率为95.0%,可见,关系-表征复杂性模型提供的分析任务复杂性的思路和方法是较为合理的。     

Neuropsychological problem-solving skills in the elderly

This article describes the performance of a representative sample of 110 participants aged from 65 to 75 years. Participants completed the Trail-Making Test, Tactual Performance Test, and Booklet Category Test. Results confirmed that previously established cutoff scores used to determine impairment are not appropriate for this age group. Significant sex differences were found for the Tactual Performance Test and Booklet Category Test. Mean scores presented in this article provide useful normative standards for the three aforementioned tasks when given to patients aged from 65 to 75 years.     

Representation and Perseveration: Influences on Young Children's Representational Insight

We carried out 3 experiments to determine what role different task demands play in 2.5-year-old children's performance on DeLoache's (1987) model-room task. The results of Experiment 1 reveal that the size of the toy to be retrieved had little bearing on performance; only the size of the spaces affected performance. Experiment 2 demonstrated that the large number of perseverative errors produced by children in these tasks was not reduced when the toy on each of the 4 test trials was changed and, thus, further suggested that characteristics of the toy had little influence on performance. Experiment 3 showed that elimination of the possibility of perseverative response through removal of the previously used hiding locations did not facilitate transfer. The results point to conceptual inflexibility or difficulty of engagement in dual representation associated with the search space as important contributors to the lack of representational insight demonstrated by 2.5-year-old children.