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.     

The left digit effect in a complex judgment task: Evaluating hypothetical college applicants

A left digit effect has been broadly observed across judgment and decision-making contexts ranging from product evaluation to medical treatment decisions to number line estimation. For example, $3.00 is judged to be a much greater cost than $2.99, and “801” is estimated strikingly too far to the right of “798” on a number line. Although the consequences of the effects for judgment and decision behavior have been documented, the sources of the effects are not well established. The goal of the current work is to extend investigations of the left digit effect to a new complex judgment activity and to assess whether the magnitude of the effect at the individual level can be predicted from performance on a simpler number skills task on which the left digit effect has also recently been observed. In three experiments (N = 434), adults completed a judgment task in which they rated the strength of hypothetical applicants for college admission and a self-paced number line estimation task. In all experiments, a small or medium left digit effect was found in the college admissions task, and a large effect was found in number line estimation. Individual-level variation was observed, but there was no relationship between the magnitudes of the effects in the two tasks. These findings provide evidence of a left digit effect in a novel multiattribute judgment task but offer no evidence that such performance can be predicted from a simple number skills task such as number line estimation.     

An fMRI study of sex differences in regional activation to a verbal and a spatial task

Sex differences in cognitive performance have been documented, women performing better on some phonological tasks and men on spatial tasks. An earlier fMRI study suggested sex differences in distributed brain activation during phonological processing, with bilateral activation seen in women while men showed primarily left-lateralized activation. This blood oxygen level-dependent fMRI study examined sex differences (14 men, 13 women) in activation for a spatial task (judgment of line orientation) compared to a verbal-reasoning task (analogies) that does not typically show sex differences. Task difficulty was manipulated. Hypothesized ROI-based analysis documented the expected left-lateralized changes for the verbal task in the inferior parietal and planum temporal regions in both men and women, but only men showed right-lateralized increase for the spatial task in these regions. Image-based analysis revealed a distributed network of cortical regions activated by the tasks, which consisted of the lateral frontal, medial frontal, mid-temporal, occipitoparietal, and occipital regions. The activation was more left lateralized for the verbal and more right for the spatial tasks, but men also showed some left activation for the spatial task, which was not seen in women. Increased task difficulty produced more distributed activation for the verbal and more circumscribed activation for the spatial task. The results suggest that failure to activate the appropriate hemisphere in regions directly involved in task performance may explain certain sex differences in performance. They also extend, for a spatial task, the principle that bilateral activation in a distributed cognitive system underlies sex differences in performance.     

中国人的群体参照记忆效应

在自我参照效应范式中加入参照认同群体加工任务,比较了中国被试在参照中国人和参照美国人进行记忆加工时的再认率及“记得”与“知道”判断的成绩。两项实验结果一致表明,参照中国人加工的再认成绩显著高于参照美国人,表明记忆加工的认同群体参照效应,而在“记得”与“知道”指标上并无差异;参照中国人加工的再认成绩和“记得”判断成绩显著低于自我参照加工。根据个体自我、关系自我和集体自我的分类方法,自我参照效应反映了个体自我对于记忆加工的影响,群体参照效应则主要反映了集体自我的影响     

Focal changes in cerebral blood flow produced by a test of right-left discrimination

A sensorimotor control activation task was used to isolate the focal cerebral blood flow changes resulting from the visual and cognitive processing of a right-left discrimination task. Eleven normal right-handed males participated. The sensorimotor control task produced significant bilateral increases in flow in most cortical channels. Significant bilateral parieto-occipital activation was found for the right-left discrimination task over and above the flow changes produced by the sensorimotor control task. The left occipital flow increase resulting from the right-left discrimination task was found to be negatively related to task performance. An inverse relationship was also found between WAIS Performance IQ and the blood flow change in the left parietal channel. These results suggest areas for further testing concerning potential individual differences in cognitive processing during the performance of a right-left discrimination task.     

Recruitment of anterior and posterior structures in lexical-semantic processing: an fMRI study comparing implicit and explicit tasks

Previous studies examining explicit semantic processing have consistently shown activation of the left inferior frontal gyrus (IFG). In contrast, implicit semantic processing tasks have shown activation in posterior areas including the superior temporal gyrus (STG) and the middle temporal gyrus (MTG) with less consistent activation in the IFG. These results raise the question whether the functional role of the IFG is related to those processes needed to make a semantic decision or to processes involved in the extraction and analysis of meaning. This study examined neural activation patterns during a semantic judgment task requiring overt semantic analysis, and then compared these activation patterns to previously obtained results using the same semantically related and unrelated word pairs in a lexical decision task which required only implicit semantic processing (Rissman, J., Eliassen, J. C., & Blumstein, S. E. (2003). An event-related fMRI investigation of implicit semantic priming. Journal of Cognitive Neuroscience, 15, 1160-1175). The behavioral results demonstrated that the tasks were equivalent in difficulty. fMRI results indicated that the IFG and STG bilaterally showed greater activation for semantically unrelated than related word pairs across the two tasks. Comparison of the two task types across conditions revealed greater activation for the semantic judgment task only in the STG bilaterally and not in the IFG. These results suggest that the pre-frontal cortex is recruited similarly in the service of both the lexical decision and semantic judgment tasks. The increased activation in the STG in the semantic judgment task reflects the greater depth of semantic processing required in this task and indicates that the STG is not simply a passive store of lexical-semantic information but is involved in the active retrieval of this information.     

Individuals and dyads in a multiple-cue judgment task: Cognitive processes and performance

Virtually all studies of multiple-cue judgment focus on the learning by individuals. In a multiple-cue judgment task the authors examined if people acquire rule or exemplar knowledge as a function of learning the task alone or in dyads. Learning in dyads was expected to promote explicit rule-based thinking as a consequence of verbalization (social abstraction effect) and to improve performance due to the larger joint exemplar knowledge base (exemplar pooling effect). In two experiments the results suggest more accurate judgment by dyads, evidence for an exemplar pooling effect, but no evidence for the social abstraction effect. In contrast to most previous research, social interaction proved beneficial and allowed the dyads to surpass their combined individual performance.     

Using Relative Confidence Judgments to Evaluate Group Effectiveness

The performance of groups can be greatly influenced by their ability to identify their best member. This study investigated this issue in the context of a quantitative judgment task. Relative confidence judgments were used to determine the extent to which group members were able to identify their best member. The effectiveness of groups was also compared across three experimental conditions that varied in terms of the specific instructions group members were given about the group discussion. Results indicate that group members were often able to identify the most accurate member even though the judgment task did not have a demonstrable solution. Groups were also at least as accurate as their best member nearly 40% of the time. The group process intervention that encouraged group members to try to determine the most accurate individual judgment fared better than the intervention that focused on intraindividual accuracy rankings. Groups in this condition also showed the strongest correspondence between identifying the best member and performing at this level. Groups assigned to an unstructured group discussion condition performed nearly as well as those assigned to the more successful of the two interventions.     

The role of temporal unpredictability for process interference and code overlap in perception-action dual tasks

Two experiments explore interference in dual tasks. The first task required perceptual judgment of the movement direction (left vs right) of a briefly presented stimulus; the second task was a tone-discrimination reaction-time (RT) task. Participants reported their judgment at leisure. In 50% of the trials they were told to ignore the stimulus (no report). The directions of stimulus movement and response in the RT task could either be the same or different, establishing cross-task compatibility (CTC) relations. We varied the degree of temporal unpredictability by using two stimulus-onset asynchronies (SOA, 100 ms vs 1200 ms) for the task stimuli. In Experiment 1, SOA was varied randomly within blocks of trials in one group and between blocks in another group. In Experiment 2, only the short SOA was used in one group and only the long SOA in another group. In both experiments, we observed substantially longer RTs with the short compared with the long SOA, regardless of whether there was temporal certainty (blocked or constant SOA) or uncertainty (random SOA) about stimulus onset. We assume that the process of encoding into short-term memory in one task interferes with concurrent retrieval processes (i.e., response selection) in the other task. This process interference effect was strongly reduced in no-report trials. Furthermore, we found shorter RT in compatible than in incompatible trials. This CTC effect diminished with long SOA but occurred even in no-report trials, implying that it refers to an automatically activated and then decaying code that primes response selection in the RT task.     

A study of syntactic processing in aphasia I: behavioral (psycholinguistic) aspects

This paper presents the results of a study of syntactically based comprehension in aphasic patients. We studied 42 patients with aphasia secondary to left hemisphere strokes and 25 control participants. We measured off-line, end-of-sentence, performance (accuracy and reaction time) in two tasks that require comprehension--enactment and sentence-picture matching--and in grammaticality judgment, with whole sentence auditory presentation. We also used sentence-picture matching and grammaticality judgment as tasks in two self-paced listening studies with the same patients to measure on-line performance. In each task and presentation format, we presented sentences that tested the ability to assign and interpret three structural contrasts chosen to examine different basic syntactic operations: actives and passives, subject and object extracted relative clauses, and reflexive pronouns and matched sentences without these elements. We examined these behavioral data to determine patterns of impairment in individual patients and in groups of patients, using correlational analyses, factor analyses, and analyses of variance. The results showed that almost no individual patients had stable deficits referable to the ability to interpret individual syntactic structures, that a variety of structural features contributed to sentence processing complexity both on-line and off-line, that correct responses were associated with normal on-line and errors with abnormal performance, and that the major determinant of performance is a factor that affected performance on all sentence types. The results indicate that the major cause of aphasic impairments of syntactically based comprehension are intermittent reductions in the processing capacity available for syntactic, interpretive, and task-related operations.     

Exploring the rabbit hole of possibilities by myself or with my group: The benefits and liabilities of activating counterfactual mind‐sets for information sharing and group coordination

The current experiment explored the effect of activating a counterfactual mind‐set on the discussion of unique information and group judgment accuracy. Evidence suggests that a counterfactual mind‐set is characterized by a focused, analytic mental state and, when activated at the group level, improves group judgment accuracy in the murder mystery paradigm (a hidden profile task). We hypothesized that the beneficial effect of the counterfactual mind‐set would only help group problem‐solving tasks if the mind‐set had been activated at the group level, allowing the analytical mind‐set to play out in an atmosphere of synergistic coordination. In contrast, if this highly focused mental state is activated at the individual level, it could impair group judgment quality because inwardly focused analytical individuals may fail to coordinate their behavior with other group members. Consistent with our hypothesis, activating a counterfactual mind‐set at the individual level had a debilitating effect on the group judgment task, whereas activating a counterfactual mind‐set at the group level had a facilitative effect, increasing information sharing, synergistic coordination and judgment accuracy. Copyright © 2004 John Wiley & Sons, Ltd.     

高边缘性人格障碍特质者负性沉浸的自我反思倾向

采用自我参照范式考察边缘性人格障碍(BPD)的自我反思特点。实验1对比高、低BPD特质被试在自我和姓名参照条件下正负性词汇的再认成绩,发现高BPD特质者在自我参照条件下的负性词汇记忆成绩显著高于低BPD特质组。实验2对高BPD特质被试进行正念自我反思训练,结果发现相对于对照组,训练组在自我参照条件下负性词汇的记忆成绩显著降低。高BPD特质者的自我反思存在负性沉浸倾向,且正念自我反思训练可以改善该倾向。     

Cognitive task effects on hemispheric blood flow in humans: Evidence for individual differences in hemispheric activation

Evidence from two indirect measures of hemispheric activity, EEG α and conjugate lateral eye movements, has pointed to the existence of individual differences in hemispheric activation. Results from a more direct indicator of hemispheric activity, regional cerebral blood flow as measured by the ¹³³Xe inhalation method, show that such individual differences can be detected in the distribution of blood in the two hemispheres and that the amount of increase in blood flow in the right relative to the left hemisphere is correlated with performance on a spatial task. These results corroborate and extend the findings from the EEG and eye movement studies and suggest that the dimension of individual differences in hemispheric activation may exert significant influence on cognitive performance and on problem-solving strategies.     

自我和物体为参照系的心理旋转分离：内旋效应

采用虚拟的旋转不同角度左、右手模型,构建“左右手判断(Left and right hand judgment: LR)”任务和“相同－不同判断(same and different judgment: SD)”任务,考察这两种实验任务是否都存在内旋效应和角度效应,以此推论被试采用何种旋转策略。结果发现：（1） 两种实验任务结果均表现出显著的角度效应。（2）在LR任务条件下,存在显著的内旋效应,而在SD任务中不存在内旋效应。从而表明当人手图片作为心理旋转材料时,它具有双重角色。被试心理旋转加工时究竟选用何种参照系的旋转策略,与实验材料和实验任务两者都密不可分     

Neural substrates of impaired categorical perception of phonemes in adult dyslexics: an fMRI study

Phonological developmental dyslexics remain impaired in phonetic categorical perception (CP) even in adulthood. We studied the brain correlates of CP in dyslexics and controls using a block design fMRI protocol and stimuli from an phonetic continuum between natural /Pa/ and /Ta/ syllables. Subjects performed a pseudo-passive listening task which does not imply voluntary categorical judgment. In the control group, categorical deviant stimuli elicited specific activations in the left angular gyrus, the right inferior frontal gyrus and the right superior cingulate cortex. These regions were not activated in the dyslexic group in which activation was observed for acoustic but not phonetic changes in stimuli. Failures to activate key regions for language perception and auditory attention in dyslexic might account for persistent deficits in phonological awareness and reading tasks.     

Differential prefrontal-temporal neural correlates of semantic processing in children

This study used functional magnetic resonance imaging (fMRI) to examine brain-behavior correlations in a group of 16 children (9- to 12-year-olds). Activation was measured during a semantic judgment task presented in either the visual or auditory modality that required the individual to determine whether a final word was related in meaning to one of two previous words (e.g., found-tank-lost). The main finding was that higher performers (i.e., accuracy) were associated with more activation in posterior representational systems including the inferior and middle temporal gyri, whereas lower performers were associated with more activation in anterior regions including the inferior and middle frontal gyri. This pattern of results was interpreted as reflecting an elaborated semantic representational system in temporal areas for the high accuracy performers that allowed them to efficiently and accurately make meaning based judgments. The low accuracy performers may have an inaccurate or weakly interconnected semantic system that results in greater use of frontal areas in a feature selection process.     

The prediction of group motor performance from individual member abilities

Two experiments were conducted to investigate the prediction of group performance on the motor-maze task from individual member abilities. In both experiments subjects performed 20 individual trials on the maze task in an initial session prior to the actual experiment. On the basis of these individual performance scores, two-person groups were formed so that the groups represented a range of average ability levels and a range of discrepancies in abilities between partners. In Experiment 1, all groups performed a cooperative and a noncooperative group task in separate sessions both involving competition with another group. Only the cooperative group task was used in Experiment 2, but all groups performed under both competitive and noncompetitive conditions. Multiple regression analyses yielded a moderate, positive relationship between member abilities and group performance in both experiments; group performance on the highly cooperative task was dominated by the lower-ability partner.     

Processes That Mediate the Relationship Between a Group Goal and Group Member Performance

The impact of a group goal on the performance of anonymous and nonin- teracting group members performing an additive group task was tested. Pro- cesses believed to mediate the effect, the role of self-set individual goals, the impact of information about the group's previous performance on the task (group knowledge of results; GRPKR) on goal commitment, and the motiva- tional basis of the goal were also assessed. Seventeen groups of three to five people performed two trials of an idea generation task. In the GOAL/GRPKR condition, group members were assigned a group goal for Session 2 and received information about the group's performance for Session 1. In the goal without knowledge of results (GOAL/NOKR) condition, group mem- bers were assigned a group goal for Session 2 without GRPKR. In the NO- GOAL condition, group members worked without a goal and without GRPKR. In each condition, group members worked on the task without talk- ing to other group members and individual contributions to the group prod- uct were unknown to others. Self-reports of effort, changes in individual performance strategies from Rial 1 to Rial 2, self-set individual goals, goal commitment, and personal challenge were collected. Results showed that (a) group members working toward a performance goal outperformed those working without a goal, b) information about the group's previous perfor- mance on the task did not influence commitment to the goal or performance, (c) changes in individual performance strategies mediated the group goal ef- fect but self-reports of effort invested in the task did not, (d) g m ~ p members working toward a group goal felt more personal challenge than group mem- bers working without a goal, and (e) self-set individual goals can not account for the group goal effect. The implications of these results for models of group goals and group performance are discussed.     

Using fMRI to study recovery from acquired dysphasia

We have used functional magnetic resonance imaging (fMRI) to characterize brain activations associated with two distinct language tasks performed by a 28-year-old woman after partial recovery from dysphasia due to a left frontal hemispheric ischemic stroke. MRI showed that her ischemic lesion extended posteriorly from the left inferior frontal to the perisylvian cortex. fMRI scans of both language tasks revealed substantial differences in activation pattern relative to controls. The nature of this difference was task-specific. During performance of a verbal semantic decision task, the patient, in contrast to controls, activated a network of brain areas that excluded the inferior frontal gyrus (in either hemisphere). A second task involving rhyme judgment was designed to place a heavier cognitive load on language production processes and activated the left inferior frontal gyrus (Broca's area) strongly in normal controls. During this task, the most prominent frontal activation in the patient occurred in the right homologue of Broca's area. Subsequent analysis of this data by methods able to deal with responses of changing amplitude revealed additional, less sustained recruitment by the patient of cortex adjacent to the infarct in the region inferior to Broca's area during rhyming. These results suggest that in addition to changes in cognitive strategy, recovery from dysphasia could be mediated by both the preservation of neuronal networks in and around the infarct and the use of homologous regions in the contralateral hemisphere.     

Cognitive, perceptual-speed, and psychomotor determinants of individual differences during skill acquisition

The authors describe a series of experiments that explore 3 major ability determinants of individual differences in skill acquisition in the context of prior theory (e.g., P.L. Ackerman, 1988) and subsequent empirical and theoretical research. Experiment 1 assessed the predictability of individual differences in asymptotic skill levels on the Kanfer-Ackerman Air Traffic Controller (ATC) task. Experiment 2 provided an exploration of the construct space underlying perceptual-speed abilities. Experiment 3 concerned an evaluation of theoretical predictions for individual differences in performance over skill development in a complex air traffic control simulation task (TRACON) and the ATC task, with an extensive battery of general and perceptual-speed measures, along with a newly developed PC-based suite of psychomotor ability measures. Evidence addressing the predictability of individual differences in performance at early, intermediate, and asymptotic levels of practice is presented.