Strategy selection for cognitive skill acquisition depends on task demands and working memory capacity

The involvement of working memory capacity (WMC) in ruled-based cognitive skill acquisition is well-established, but the duration of its involvement and its role in learning strategy selection are less certain. Participants (N = 610) learned four logic rules, their corresponding symbols, or logic gates, and the appropriate input–output combinations in three-gate circuit patterns. Participants practiced 120 repetitions of each rule (480 total gates) over the course of 10 training blocks. Memory load varied between subjects. The confluence of task demands and individual differences in WMC (N = 518) dramatically affected speed–accuracy tradeoffs and strategic use of a computerized help function. Cluster analysis revealed five distinct groups of participants based on the combination of response accuracy, latency, and help use. Some groups with moderate to high mean WMC acquired the task with predictable performance patterns. Other groups, prevalently under a memory load and with low mean WMC, failed to learn or overused help.     

Study on EEG power and coherence in patients with mild cognitive impairment during working memory task

To investigate the features of electroencephalography (EEG) power and coherence at rest and during a working memory task of patients with mild cognitive impairment (MCI). Thirty-five patients (17 males, 18 females; 52～71 years old) and 34 sex- and age-matched controls (17 males, 17 females; 51～63 years old) were recruited in the present study. Mini-Mental State Examination (MMSE) of 35 patients with MCI and 34 normal controls revealed that the scores of MCI patients did not differ significantly from those of normal controls (P＞0.05). Then, EEGs at rest and during working memory task with three levels of working memory load were recorded. The EEG power was computed over 10 channels: right and left frontal (F3, F4), central (C3,C4), parietal (P3, P4), temporal (TS, T6) and occipital (O1, O2); inter-hemispheric coherences were computed from five electrode pairs of F3-F4, C3-C4, P3-P4, T5-T6 and O1-O2 for delta (1.0～3.5 Hz), theta (4.0～7.5 Hz), alpha-1 (8.0～10.0 Hz), alpha-2 (10.5～13.0 Hz), beta-1 (13.5～18.0 Hz) and beta-2 (18.5～30.0 Hz) frequency bands. All values of the EEG power of MCI patients were found to be higher than those of normal controls at rest and during working memory tasks. Furthermore, the values of EEG power in the theta, alpha-1, alpha-2 and beta-1 bands of patients with MCI were significantly high (P＜0.05) in comparison with those of normal controls. Correlation analysis indicated a significant negative correlation between the EEG powers and MMSE scores. In addition, during working memory tasks, the EEG coherences in all bands were significantly higher in the MCI group in comparison with those in the control group (P＜0.05). However, there was no significant difference in EEG coherences between two groups at rest. These findings comprise evidence that MCI patients have higher EEG power at rest, and higher EEG power and coherence during working conditions. It suggests that MCI may be associated with compensatory processes at rest and during working memory tasks. Moreover, failure of normal cortical connections may be exist in MCI patients.     

Characteristics of pigeons’ spatial working memory in an open-field task

Although pigeons seem to require special training before they will display accurate spatial working memory in radial-arm mazes, they readily show accurate working memory for recently visited feeder locations in an open-field analog of the radial maze. In this task, pigeons forage among sites located on the floor of an open room, with no constraints on the path they take between sites. Experiment 1 suggested that pigeons’ working memory for recently visited sites is facilitated if they are permitted to develop a stable reference memory “map” of the location of the sites with respect to landmarks in the room: Pigeons for which the landmarks remained constant from day to day displayed more accurate working memory than did pigeons for which the landmarks were rearranged between daily trials. The second experiment investigated the durability of pigeons’ working memory, using a forced-choice procedure. Accuracy remained high for retention intervals of up to 32 min, but dropped significantly with a 2-h delay.     

Age-related differences in rats’ spontaneous alternation

Fifteen-day-old rats made random choices in a T-maze, while adult levels of alternation (approximately 70%) were noted among 30-day-olds. Also, younger pups were insensitive to a lengthening of the intertrial interval, unlike older animals whose rate of alternation decreased when a 1-h delay was interposed between arm entries. These findings are consistent with the hypothesis that hippocampal development is a factor in the ontogeny of postweaning locomotion. The unsystematic pattern of goal-arm selections among 15-day-olds suggests that ontongenetic variation in the utilization of stimuli may underlie developmental shifts in spontaneous alternation.     

Inter-and intra-hemispheric EEG coherence in patients with mild cognitive impairment at rest and during working memory task

Objective： To assess functional relationship by calculating inter- and intra-hemispheric electroencephalography （EEG） coherence at rest and during a working memory task of patients with mild cognitive impairment （MCI）. Methods： The sample consisted of 69 subjects： 35 patients （n = 17 males, n = 18 females; 52-71 years old） and 34 normal controls （n = 17 males, n = 17 females; 51 -63 years old）. Mini-mental state examination （MMSE） of two groups revealed that the scores of MCI patients did not differ significantly from those of normal controls （P〉0.05）. In EEG recording, subjects were performed at rest and during working memory task. EEG signals from F3-F4, C3-C4, P3-P4, T5-T6 and O1-O2 electrode pairs are resulted from the inter-hemispheric action, and EEG signals from F3-C3, F4-C4, C3-P3, C4-P4, P3-O1, P4-O2, T5-C3, T6-C4, T5-P3 and T6-P4 electrode pairs are resulted from the intra-hemispheric action for delta （1.0-3.5 Hz）, theta （4.0-7.5 Hz）, alpha-1 （8.0-10.0 Hz）, alpha-2 （10.5-13.0 Hz）, beta-1 （13.5-18.0 Hz） and beta-2 （18.5-30.0 Hz） frequency bands. The influence of inter- and intra-hemispheric coherence on EEG activity with eyes closed was examined using fast Fourier transformation from the 16 sampled channels. Results： During working memory tasks, the inter- and intra-hemispheric EEG coherences in all bands were significantly higher in the MCI group in comparison with those in the control group （P〈0.05）. However, there was no significant difference in inter- and intra-hemispheric EEG coherences between two groups at rest. Conclusion： Experimental results comprise evidence that MCI patients have higher degree of functional connectivity between hemispheres and in hemispheres during working condition, It suggests that MCI may be associated with compensatory processes during working memory tasks between hemispheres and in hemispheres. Moreover, failure of normal cortical connections may exist in MCI patients.     

Population differences in constructive memory

An experiment was conducted to evaluate constructive memory in fourth-grade low-SES black and middle-SES white children. The children were read nine short passages; each passage was composed of two premise statements and a filler sentence. The children were tested by a recognition procedure. Thirty-six test sentences were presented randomly. Four sentences were associated with each passage (true premise, false premise, true inference, and false inference). Subjects were asked to make yes/no recognition decisions based on whether the test sentence was identical to a sentence presented at study. Middle-SES white children made few errors, except to true inference test sentences. This pattern of performance is consistent with the constructive view of memory. Low-SES black children also had a high error rate to true inference items. However, this outcome may not reflect constructive memory because they also had a high error rate to some of the other types of test sentences.     

Alpha spectral power and coherence in the patients with mild cognitive impairment during a three-level working memory task

Objective: The functional relationship between calculated alpha band spectral power and inter-/intra-hemispheric coherence during a three-level working memory task of patients with mild cognitive impairment (MCI) was investigated. Methods: Subjects included 35 MCI patients according to the DSM-IV criteria (mean age: 62.3, SD: 6.5) and 34 healthy controls (mean age: 57.4, SD: 4.0) were selected from the community at large. All subjects performed a simple calculation and recall task with three levels of working memory load while electroencephalograph (EEG) signal was recorded. The spectral EEG power was computed over alpha1 (8.0～10.0 Hz) and alpha2 (10.5～13.0 Hz) frequency bands and was compared between rest stage and working memory processing stage by two-way ANOVA. Post hoc testing analyzed the differences between each two levels of working memory load during task processing. The inter-hemisphere EEG coherence of frontal (F3-F4), central (C3-C4), parietal (P3-P4), temporal (T5-T6) as well as occipital (O1-O2) was compared between MCI patients and normal controls. The EEG signals from F3-C3, F4-C4, C3-P3, C4-P4, P3-O1, P4-O2, T5-C3, T6-C4, T5-P3 and T6-P4 electrode pairs resulted from the intra-hemispheric action for alpha1 and alpha2 frequency bands. Result: There was significantly higher EEG power from MCI patients than from normal controls both at rest and during working memory processing. Significant differences existed between rest condition and three-level working memory tasks (P<0.001). The inter-and intra-hemispheric coherence during working memory tasks showed a "drop to rise" tendency compared to that at rest condition. There was significantly higher coherence in MCI patients than in the controls. When task difficulties increased, the cortical connectivity of intra-hemispheric diminished while the inter-hemispheric connectivity dominantly maintained the cognitive processing in MCI patients. Conclusion: The results of the present study indicate that the alpha frequency band may be the characteristic band in distinguishing MCI patients from normal controls during working memory tasks. MCI patients exhibit greater inter-hemispheric connectivity than intra-hemispheric connectivity when memory demands increase. MCI patients mobilize a compensatory mechanism to maintain the processing effectiveness while the processing efficiency is reduced.     

Sex-related differences on a task of volume and density

A sex-related difference, favoring boys, was found on initial performance of two samples (one British, one American) of 10- and 11-year-old children on a task of volume and density. After a period of classroom instruction that included opportunities for children to interact with appropriate materials and each other, both boys and girls performed at a higher level on the task, but the difference between them remained the same. There was no indication of a sex-related difference other than a time lag, in pattern of development of the concept. The question of why there is a sex-related difference, which persists in spite of experience and instruction, is discussed.     

Age-related differences in the organization of parent-infant interactions during picture-book reading

These observations indicate how the organization of book reading events differs when middle- to upper-class suburban parents read picture books to preverbal and verbal infants. Twelve parent-infant dyads for each group of 9-, 17-, and 27-month-old infants were videotaped in their homes. On each of three visits, two different books were read. The books either contained sentences describing the illustrations or did not contain any sentences. The quality of parent verbalizations changed with the age of the infant; parents reading to younger infants used more attention-recruiting verbalizations and more elaborations, whereas parents reading to older infants used more questions and more feedback. Analyses of sequential dependencies between categories of behaviors suggest that, across these age groups, parents monitor and attempt to maximize their infants' attention to the book. Parents' verbalizations expand from labeling comments, to sequences of labeling questions, to dialogues that exercise the growing linguistic competencies of the infant. Finally, interactions with books containing no sentences led to more verbal behaviors by the parent and more vocalizations by the infant.     

Effects of cognitive demand on situational interest and running task performances

This study examined the effect of cognitive demand on situational interest and performance using running tasks in physical education. Adolescents (N = 179) participated in a field study involving three different levels of cognitive demand. Running performances and situational interest were measured four times with a testing interval of seven days. Results from multivariate analyses of covariance suggested that cognitive demand had a significant effect on situational interest and running performances. Higher cognitive demand led to higher levels of situational interest. Situational interest was weakly or moderately correlated with running performances (|r| = .17?.40), yet students reported significantly lower performance when the perceived interest was the highest. These findings suggest the importance of designing instructional tasks with moderate cognitive demand to optimally preserve situational interest and performance in physical education. The findings also help further conceptualise the relations among cognitive demand, situational interest and performance.     

The episodic/semantic memory distinction as an heuristic in the study of instructional effects on cognitive structure

Previous attempts to measure the effects of instruction on students' cognitive structure have produced inconsistent and ambiguous findings. One reason may be that researchers have not distinguished between well-learned, abstracted information and memorized facts or formulas. Using the distinction between episodic and semantic memory as an heuristic, a procedure was designed to increase the likelihood that student performance on structure tasks was indicative of semantic rather than episodic memory. Significant correlations between measures of cognitive structure and performance on achievement test items were observed. In addition, partial correlations revealed that the measures of cognitive structure are correlated with the achievement items tapping higher-order cognitive processes and not with items tapping lower-order processes. These results are interpreted as supporting the argument that related research needs to be guided by theory-based definitions of cognitive structure.     

Gender differences in cognitive abilities of reading-disabled twins

Gender differences were assessed in three research-identified samples of children who were members of twin pairs: (1) 120 male and 124 female probands from same-sex identical and fraternal twin pairs in which at least one member of each pair is reading disabled; (2) a comparison sample of 148 males and 161 females from same-sex twin pairs with no history of reading problems; and (3) 34 pairs of opposite-sex fraternal twin pairs in which at least one member of each pair is reading disabled. Results of multivariate analyses of variance of psychometric test data from the two samples of same-sex twin pairs, in which the male and female subjects were reared in different homes, suggest that profiles of gender differences are similar in reading-disabled and control children. Moreover, this pattern of gender differences also tended to occur in opposite-sex twin pairs, who shared prenatal, as well as early postnatal, environmental influences. In general, reading-disabled males obtained higher average scores than affected females on Wechsler (1974, 1981) Verbal and Performance IQ, but lower scores on Reading Recognition and Spelling subtests of the Peabody Individual Achievement Test (Dunn and Markwardt 1970). With regard to the Wechsler subtests, reading-disabled males achieved higher average scores on Information, Picture Completion, Block Design, and Object Assembly, but lower scores on Coding. Although significant and relatively consistent gender differences in cognitive measures were found in three samples included in this study, these differences account for only a small portion of the observed variance. This work was supported in part by a program project grant from NICHD (HD-11681), and the report was prepared while J.J. Gillis was supported by NICHD training grant HD-07289.     

Recall performance on a central-incidental memory task by profoundly deaf children.

Bebko (1984) reported that deaf children tend not to use spontaneously active memory strategies such as rehearsal in tasks requiring recall of ordered, temporal information. The present study investigated whether this tendency is task specific or generalized to other experimental paradigms. A central-incidental paradigm was used with profoundly deaf children and hearing children 6 to 13 years of age. The results for the hearing students replicated previous studies: central recall increased with age, but incidental recall changed little. For the deaf children, the results initially appeared very similar to those of the hearing children. However, on closer examination, the rehearsal strategies of the deaf students seemed less effective in mediating their recall. They apparently compensated for these difficulties by capitalizing on unique spatial features of the task, leading to recall levels comparable to those of the hearing students. Therefore, similar performance may not have been the result of equal strategy use but, rather, of the use of additional strategies by the deaf students. This study reinforced the need to provide additional training for deaf students in the use of memory strategies such as rehearsal when information is to be remembered in a sequential manner.     

Individual differences in cognitive synthesis: An M-capacity analysis

Individual differences in children's propensity to demonstrate cognitive synthesis were evaluated using an artificial reading task. Six-year-olds were asked to demonstrate the meaning of various sentences constructed of logographs, or whole-word symbols, which were arranged in either a meaningful (i.e., grammatical) or scrambled (i.e., ungrammatical) order. Some children demonstrated the sentences in a synthesized mode (expressing a single idea unit), while others used a nonsynthesized mode (expressing the meanings of individual logographs). Overall, synthesizers had a larger attentional reserve, or M-capacity, than nonsynthesizers. The two groups did not differ significantly in age, intellectual level, or reading achievement. As predicted by their larger M-capacity, synthesizers demonstrated from memory significantly more items from meaningful sentences than nonsynthesizers. However, when synthesizers attempted to integrate the scrambled sentences, the excessive operative schemes needed to reorganize the items reduced their recall performance to the level of nonsynthesizers.     

Individual differences in a positional learning task across the adult lifespan

This study aimed at modeling individual and average non-linear trajectories of positional learning using a structured latent growth curve approach. The model is based on an exponential function which encompasses three parameters: Initial performance, learning rate, and asymptotic performance. These learning parameters were compared in a positional learning task administered to a sample comprising the whole adult lifespan (N = 527; age range: 20 years to 89.3 years; M_age = 52.95, SD_age = 17.37). Additionally, three explanatory variables, age, speed of information processing, and educational level were included in the analyses. All three learning parameters showed reliable individual differences. The correlations between the learning parameters indicated that those participants with high learning rates needed more trials to achieve their asymptotic performance and those who recalled more items initially also had a higher asymptotic performance. Older persons showed lower initial performance and lower asymptotic performance, whereas speed of information processing was positively associated only with initial performance. Persons with more years of formal education had a higher initial performance and a higher asymptotic performance. The learning rate, in turn, appeared to be unaffected by all three predictor variables.     

Localizing the development of ability differences in organized memory

Although it is well know that learning disabled children tend to perform more poorly than normally achieving children on most memory tasks, the basis of this poor performance remains unclear. Recently, evidence has been accumulating which suggests that disabled children have difficulty with the basic processes of storage and retrieval. The purpose of the present research was to investigate this hypothesis using a recently developed model of memory that provides a factoring procedure for measuring storage and retrieval processes. In particular, we were interested in localizing the source of the development of ability differences in organized recall in early (grade 2) and later (grade 6) elementary school. All of the 600 children who participated had measured IQs in the 97–107 range; however, the disabled students were at least 1 year behind in either reading or arithmetic but not both. All of the children learned a 16-item list that was either unrelated or categorized using either a free or cued recall procedure. The results indicated that while ability differences were present at storage and retrieval, differences tended to be larger at retrieval than at storage, on categorized rather than on uncategorized lists, and in the cued rather than in the free recall conditions. These results illustrate that the ability to execute purposive components of retrieval develops more slowly in disabled than in nondisabled children. Consequently, it is these processes that should be the primary target in remedial memory programs.