Individual differences in working memory capacity predict action monitoring and the error-related negativity

Neuroscience suggests that the anterior cingulate cortex (ACC) is responsible for conflict monitoring and the detection of errors in cognitive tasks, thereby contributing to the implementation of attentional control. Though individual differences in frontally mediated goal maintenance have clearly been shown to influence outward behavior in interference-rich contexts, it is unclear whether corresponding differences exist in neural responses that arise out of the ACC. To investigate this possibility, we conducted an electrophysiological study using a variant of the Simon Task, recording event-related potentials (ERPs) in healthy normal individuals with varying working memory capacity (high vs. low spans; a behavioral proxy for variability in goal maintenance). Primary analyses focused on the magnitude of the error-related negativity (ERN), a response-locked ERP component associated with the commission of errors thought to arise because of action monitoring in the ACC. Our results revealed that frontally mediated working memory capacity may alter error monitoring by the ACC, with high spans showing a greater ERN than low spans. These individual differences were also observed in the posterror positivity, a response-locked ERP component associated with updating cognitive strategies, suggesting greater awareness of errors with increased working memory capacity. These results are interpreted within 2-process models of attentional control, suggesting individuals with greater working memory capacity may better maintain task goals by more strongly biasing neural activity in frontal-executive networks.     

Developmental differences in reactions to children labeled mentally retarded

In an attempt to examine age-related differences in response to the mental retardation label, 48 4th and 5th graders and 48 11th and 12th graders were told of a child of their own age and sex who was either labeled mentally retarded or unlabeled and who performed either competently or incompetently in giving a report. Incompetent target children were viewed more negatively than competent ones at both grade levels. The mental retardation label had less generalized impacts, leading girls but not boys (a) to cite lack of ability as the reason for a retarded child's failure, and (b) to hold low expectations that retarded targets would hold jobs, marry, or have children. A developmental shift in responses to the label was evident only on a trait perception measure; younger children stigmatized retarded targets, while older children granted special dispensation of a failing retarded child by viewing him or her more positively than a similarly incompetent but unlabeled child. Since only adolescent boys showed special dispensation, even though girls were more generally attentive to the label, both sex and age differences warrant further examination.     

Developmental differences in shape processing

Considerable evidence indicates that shape similarity plays a major role in object recognition, identification and categorization. However, little is known about shape processing and its development. Across four experiments, we addressed two related questions. First, what makes objects similar in shape? Second, how does the processing of shape similarity develop? We specifically asked whether children and adults determine shape similarity by using categories (e.g., straight vs. curved), as proposed by Biederman (1987), or whether they treat all shape variability uniformly, as proposed by Ullman (1998). Findings from Experiments 1 and 2 suggest that adults and 7-year-olds generally engage in a process in which they impose categories on shape variation and judge objects that fall within those categories as being similar in shape. Four-year-olds are far less likely to engage in such a process. Experiments 3 and 4 address whether 4-year-olds are more likely to treat shape similarity categorically (as older children and adults do) when the objects are given familiar names, functions, and internal properties. Naming did lead to more advanced treatment of shape similarity in some cases. Overall, these findings provide evidence of developmental differences in shape processing and suggest that knowledge of abstract properties of objects may affect the calculation of shape similarity.     

Developmental differences in response processing

Three age groups (kindergartners, fourth graders, and adults) were compared in their processing of response decisions in a two-choice reaction time task. Manipulation of spatial stimulus-response compatibility resulted in age-related differential effects on reaction time performance. For the younger children, selecting the appropriate response for an incompatibly paired stimulus light required proportionately longer processing time than for older subjects. Similar results were not found for performance under varying levels of response discriminability.     

Response monitoring, the error-related negativity, and differences in social behavior in autism

Children with autism not only display social impairments but also significant individual differences in social development. Understanding the source of these differences, as well as the nature of social impairments, is important for improved diagnosis and treatments for these children. Current theory and research suggests that individual differences in response monitoring, a specific function of the anterior cingulate cortex (ACC), may contribute to social-emotional and social-cognitive impairments and individual differences in autism. To examine this hypothesis, we used a modified flanker task to assess an ERP index of response monitoring, the error-related negativity (ERN), in a sample of higher function children with autism (HFA) and an IQ-matched control sample. The results revealed a significant Diagnostic group by Verbal IQ interaction on ERN amplitude indicating that the most verbally capable HFA children displayed significantly larger ERN amplitudes than did the control children. Within the HFA sample, greater ERN amplitude was also related to parent reports of fewer symptoms of social interaction impairments, fewer internalizing problems, but more externalizing problems, although these associations were reduced to nonsignificance when medication status was controlled. The latter results complement previous observations from imaging studies of a significant association between ACC activity and social symptoms and impairments in autism. The implications of these results for future research on brain-behavior relations, as well as treatment related research with children with autism are discussed.     

Developmental differences in mental rotation.

A reaction time paradigm was used to investigate developmental differences in ability to rotate and compare imaginal representations. Third grade, fifth grade, and college students (ages 9, 11, and 20 years, respectively) were required to determine whether a letter of the alphabet was presented in its backward or normal position. Letters were presented at 0, 60, 120, 180, 240, or 300° orientations from upright. Subjects were given no advance information about a test letter, or they were given identity and orientation information. In the no information condition, reaction time increased for all age groups as a function of the departure in orientation of the test letter from an upright position. In the advance information condition, reaction time remained uniform across orientation for only the college subjects. The developmental implications of these findings are discussed.     

Developmental differences in children's context-dependent word learning

In this study, 2.5-, 3-, and 4-year-olds (N = 108) participated in a novel noun generalization task in which background context was manipulated. During the learning phase of each trial, children were presented with exemplars in one or multiple background contexts. At the test, children were asked to generalize to a novel exemplar in either the same or a different context. The 2.5-year-olds’ performance was supported by matching contexts; otherwise, children in this age group demonstrated context dependent generalization. The 3-year-olds’ performance was also supported by matching contexts; however, children in this age group were aided by training in multiple contexts as well. Finally, the 4-year-olds demonstrated high performance in all conditions. The results are discussed in terms of the relationship between word learning and memory processes; both general memory development and memory developments specific to word learning (e.g., retention of linguistic labels) are likely to support word learning and generalization.     

Developmental differences in children's labeling of movement

Children's encoding of information, specifically, the correct use and application of labels, is one factor frequently used to account for developmental differences in verbal learning. Labels may also be used in connection with remembering positional movements. The purpose of this study was to evaluate developmental differences in the effects of labels upon remembering movements. In addition, the study evaluated whether better or poorer labeling strategies would increase or decrease performance in the age groups studied. Subjects consisted of kindergarten children (N=27), fifth grade children (N=27), and adults (N=27) randomly assigned within each age level to one of three groups: subjective label, irrelevant label, and relevant label. Subjects were tested on a two-dimensional positioning task allowing estimates of radial, location, and distance errors. Results indicated that relevant labels (clock face) improved performance for remembering positions within all age conditions. Of major interest was the finding that relevant labels increased performance of the kindergarten children to the approximate level of the irrelevant label (animals) group for fifth graders. The same finding was evident for the fifth graders with the relevant label group approximating performance of adults forced to use a less sophisticated strategy (irrelevant label, i.e., animals). This finding suggests that a significant portion of the differences between younger and older children and adult performance is due to the processing deficit of poor encoding strategies used by children.     

Developmental differences in rehearsal and free recall

The purpose of this experiment was to analyze developmental differences in rehearsal strategies which may mediate the commonly found age effect on free recall. As expected, significant age differences in recall were found; analysis of rehearsal strategies showed that fifth and eighth graders tended to repeat stimulus words immediately after presentation, and not enter items into subsequent rehearsal sets. Adults, in contrast, tended to reenter items for additional rehearsal, and had larger rehearsal buffers. Immediate repetition may have served as additional massed presentation trials, which are less consequential for learning than later reentry of items (spaced trials). It was inferred that children engaged primarily in maintenance rehearsal, and adults in both maintenance and elaborative rehearsal.     

Age-related differences in working memory: ERPs reveal age-related delays in selection- and inhibition-related processes

Faulty inhibition is implicated in age-related working memory decline. ERP signs of selection and inhibition of items in working memory (WM) are, respectively, a cue-locked parietal positivity (～350 ms) and a probe-locked frontal negativity (～520 ms). To determine when in the older age range differences in selective and inhibitory processes might occur, ERPs were recorded in a WM task from 20 young (20–28), 20 young–old (60–70), and 20 old–old (71–82) adults. A 4-digit display was followed by a cue indicating which 2 of 4 digits were relevant. Proactive interference (PI), the reaction time difference between a matching and non-matching to-be-ignored digit was larger, relative to the young, in both older groups. Compared to the young, both the cue- and probe-locked activities were prolonged in the older groups. Although there were no topographic differences among the age groups, the prolonged PI and associated ERPs suggest a relative age-related deficit in inhibition.     

Relationship between career maturity and self-concepts of suburban and urban middle- and urban lower-class preadolescent black males

The relationship between career maturity and self-concepts of 252 sixth-grade black males was investigated. Student samples of suburban and urban middle- and urban lower-class were drawn from 42 different school settings located in Monroe, Erie, and Westchester Counties of New York State. The Attitude Scale of the Career Maturity Inventory and the Coopersmith Self-Esteem Inventory were used to assess the association of career maturity and self-concepts. Results indicated relatively weak-positive relationships between career maturity and self-concepts. Significant career maturity differences were found. However, self-concepts of the three groups were not statistically significantly different. Of the set of independent variables predicting and estimating variance accounted for (socioeconomic status, family intactness, place of residence, and reading), socioeconomic status was found to have the strongest predictive value on career maturity. It was suggested that researchers examine elementary school black students' career development in view of the group with whom they identify most.     

Developmental differences in children's understanding of epistemic authority

An experiment was carried out to examine age differences in children's understanding of epistemic authority and its role in conversation. Two hundred and forty-six children from two age groups (6–7 and 11–12 years) were asked to make an independent judgement as to the equality or inequality of two lines in an optical illusion. Experimental conditions varied; ‘expertise’ in the task was given by training in a measurement algorithm and ‘familiarity with related stimuli’ by being shown illusions other than the test stimulus in training. Subjects who had answered independently that the lines were equal in length were paired with a same-age subject who had responded that they were unequal, and the two were then asked to arrive at agreement. Results showed that younger children rely on external features of a situation in justifying their beliefs. Gender differences in conversations suggest younger children have difficulty differentiating status and knowledge attributes of authority. Older children displayed an awareness of self as a necessarily autonomous element in the process of knowledge acquisition. Unexpected gender effects of stimulus familiarity in the process of persuasion are probably due to differences in subjects' behavioural styles.     

Developmental differences in the allocation of processing capacity

Recently psychologists have formulated a comprehensive view of attention involving allocation of processing capacity. Although developmental changes in processing capacity have been proposed as one source of age differences in certain cognitive skills, there has been little systematic investigation of this hypothesis. In the present study, second and sixth graders and adults (8, 12, and 20 years of age, respectively) performed a letter-matching task (primary task) concurrently with an auditory detection task (secondary task). Changes in reaction time in the secondary task as a function of manipulations of the primary task were used to estimate capacity allocation to the primary task. Primary task variables included stage of processing (alerting, encoding, rehearsing, responding) and matching condition (physical-identity vs name-identity matching). Age differences in secondary task performance were found to be related to stage of processing but not to matching condition. Earlier stages of the letter match task (alerting, encoding) required somewhat more capacity allocation in younger subjects. Later stages (rehearsing, responding) made substantially higher demands on capacity in children. Capacity allocation may be an important cognitive variable mediating developmental differences in basic information processing skills, and may underlie age trends found in performance of certain complex cognitive tasks.     

Developmental differences in cognitive diatheses for child depression

We studied developmental changes in the relation between cognitive style (i.e., attributional style and cognitive errors) and depression in children. Subjects included 409 fourth-, sixth-, and eighth-grade school children. We hypothesized (1) that evidence congruent with a cognitive diathesis model of depression would emerge with development across middle childhood, (2) that Event × Cognitive Style × Age interactions would be specific to some domains of stressful events but not others, and (3) that interactions would be especially prominent in domains that children regarded as personally important. Hierarchical multiple regressions indicated that cognitive style moderated the relation between events and self-reported depressive symptoms only in later childhood, and that such interactions were specific to certain domains of stressful events and cognitions. The importance of distinguishing among types of stress and cognitions in future tests of diathesis-stress models of childhood depression are discussed. Implications of developmental differences in the psychopathology of child depression also emerge.     

Developmental and individual differences in visual memory span

The effects of chronological age (5+, 7+, 10+, and adult), articulatory suppression and spatial ability were assessed on three measures (recognition memory, partial recall, and free recall) of visual memory span for patterns, using a procedure devised by Wilson, Scott & Power (1987). Although span increased into adulthood for all three tasks, concurrent articulatory suppression acted to reduce span for the 10-year-old and adult subjects. The ability to generate accurate visuo-spatial representations at retrieval is perfectly well developed by 7 years of age. Speed of response was lengthened for the youngest age group, but was immune to the effects of concurrent articulatory suppression. Good spatial ability was associated with higher span estimates on all tasks, regardless of age. Whilst the data support the existence of a system for representing visual patterns, which increases in capacity with increasing chronological age, the system (or processes accessing it at retrieval) is not immune to verbal recoding strategies. The independent association of spatial ability with span is taken to imply that nonverbal encoding and/or maintenance strategies can act to boost visual span from at least 5 years of age.     

Developmental and individual differences in pure numerical estimation

The authors examined developmental and individual differences in pure numerical estimation, the type of estimation that depends solely on knowledge of numbers. Children between kindergarten and 4th grade were asked to solve 4 types of numerical estimation problems: computational, numerosity, measurement, and number line. In Experiment 1, kindergartners and 1st, 2nd, and 3rd graders were presented problems involving the numbers 0-100; in Experiment 2, 2nd and 4th graders were presented problems involving the numbers 0-1,000. Parallel developmental trends, involving increasing reliance on linear representations of numbers and decreasing reliance on logarithmic ones, emerged across different types of estimation. Consistent individual differences across tasks were also apparent, and all types of estimation skill were positively related to math achievement test scores. Implications for understanding of mathematics learning in general are discussed.     

Developmental differences in the impact of contextual factors on susceptibility to retroactive interference

The influence of contextual similarity on children’s recognition memory performance was examined using a retroactive interference paradigm. In the study, 9- and 12-year-olds were randomly assigned to one of two contextual conditions. In both conditions, target and interfering information were presented in distinctive contexts by using different modalities (pictures and words, respectively). However, in one condition the test was presented in the same context as the target information (picture–word–picture [PWP] condition), whereas in the other condition the test was presented in the same context as the interfering information (picture–word–word [PWW] condition). Performance in these conditions was compared with performance in a noninterference control condition (picture–word [P-W]). As predicted, overall recognition performance in the PWP condition was significantly better than in the PWW condition. However, whereas in the PWP condition there was no age difference in performance, in the PWW condition the 12-year-old group produced significantly more hits and fewer false alarms than the 9-year-old group. The theoretical implications of the results are discussed in reference to the effortful engagement of developmentally dependent executive control processes.     

Individual differences in ERPs during mental rotation of characters: Lateralization,and performance level

The cognitive process of imaging an object turning around is called mental rotation. Many studies have been put forward analyzing mental rotation by means of event-related potentials (ERPs). Event-related potentials (ERPs) were measured during mental rotation of characters in a sample (N = 82) with a sufficient size to obtain even small effects. A bilateral ERP amplitude modulation as a function of angular displacement was observed at parietal leads without any lateralization. Sex had no effect on mental rotation of characters, neither with respect to performance nor with respect to brain potentials. When the sample was split into groups of high- and low-performers, however, the results indicated (a) in line with the idea of neural efficiency substantially larger amplitudes for low-performers; (b) that the smaller amplitudes of the high-performers involved larger parietal networks; and (c) a left-parietal disengagement of neural activity for high-performers but a right-parietal disengagement for low-performers. The latter finding became evident through an analysis of internal consistencies of ERP amplitudes across conditions and performance levels, showing that internal consistencies were reduced at all three leads in the high-performance group for the biggest rotation angle, relative the other conditions and the low-performing group.