Effects of practice and positional variables in acquisition of a complex psychomotor skill

40 Navy subjects practiced a three-dimensional tracking task in two positions (the apparatus either in front of,, or above, the subject) under distributed and massed practice schedules to determine the effects of these variables on acquisition of skill. Distributed and massed practice were defined in terms of trial (4 1/2 and 9 min.) and session (1 and 2 hr.) lengths with the subjects equally divided into these four groups: distributed trials, distributed sessions; distributed trials, massed sessions; massed trials, distributed sessions; and massed trials, massed sessions. Total training (practice and rest) time was identical for all groups. Results indicated that task position was a relevant variable in acquisition of skill, i.e. different practice schedules were optimal for the two positions studied.     

Neurophysiological indices of strategy development and skill acquisition

In order to examine neurophysiological changes associated with the development of cognitive and visuomotor strategies and skills, spectral features of the EEG were measured as participants learned to perform new tasks. In one experiment eight individuals practiced working memory tasks that required development of either spatial or verbal rehearsal and updating strategies. In a second experiment six individuals practiced a video game with a difficult visuomotor tracking component. The alpha rhythm, which is attenuated by functional cortical activation, was affected by task practice. In both experiments, a lower-frequency, centrally distributed alpha component increased between practice sessions in a task-independent fashion, reflecting an overall decrease in the extent of cortical activation after practice. A second, higher-frequency, posterior component of the alpha rhythm displayed task-specific practice effects. Practice in the verbal working memory task resulted in an increase of this signal over right posterior regions, an effect not seen after practice with the spatial working memory task or with the video game. This between-task difference presumably reflects a continued involvement of the posterior region of the right hemisphere in tasks that invoke visuospatial processes. This finding thus provides neurophysiological evidence for the formation of a task-specific neurocognitive strategy. In the second experiment a third component of the alpha rhythm, localized over somatomotor cortex, was enhanced in conjunction with acquisition of tracking skill. These alpha band results suggest that cortical regions not necessary for task performance become less active as skills develop. In both experiments the frontal midline (Fm) theta rhythm also displayed increases over the course of test sessions. This signal is associated with states of focused concentration, and its enhancement might reflect the conscious control over attention associated with maintenance of a task-appropriate mental set. Overall, the results suggest that the EEG can be used to monitor practice-related changes in the patterns of cortical activity that are associated with task processing. Additionally, these results highlight the importance of ensuring that subjects have developed stable strategies for performance before drawing inferences about the functional architecture underlying specific cognitive processes.     

Fatigue contributes to the strength training stimulus

To investigate the role of fatigue in strength training, strength increases produced by a training protocol in which subjects rested between contractions were compared with those produced when subjects did not rest. Forty-two healthy subjects were randomly allocated to either a no-rest group, a rest group, or a control group. Subjects in the two training groups trained their elbow flexor muscles by lifting a 6RM weight 6-10 times on 3 d each week for 6 wk. Subjects in the no-rest group performed repeated lifts without resting, whereas subjects in the rest group rested for 30 s between lifts. Both training groups performed the same number of lifts at the same relative intensity. The control group did not train. Subjects who trained without rests experienced significantly greater mean increases in dynamic strength (56.3% +/- 6.8% (SD)) than subjects who trained with rests (41.2% +/- 6.6%), and both training groups experienced significantly greater mean increases in dynamic strength than the control group (19.7% +/- 6.6%). It was concluded that greater short-term strength increases are achieved when subjects are required to lift training weights without resting. These findings suggest that processes associated with fatigue contribute to the strength training stimulus.     

Aging, practice, and perceptual tasks: A diffusion model analysis.

Practice effects were examined in a masked letter discrimination task and a masked brightness discrimination task for college-age and 60- to 75-year-old subjects. The diffusion model (Ratcliff, 1978) was fit to the response time and accuracy data and used to extract estimates of components of processing from the data. Relative to young subjects, the older subjects began the experiments with slower and less accurate performance; however, across sessions their accuracy improved because the quality of the information on which their decisions were based improved, and this, along with reduced decision criteria, led to shorter response times. For the brightness, but not the letter, discrimination task, the older subjects' performance matched that of the younger group by the end of 4 sessions, except that their nondecision components of processing were slightly slower. These analyses illustrate how a well-specified model can provide a unified view of multiple aspects of data that are often interpreted separately. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dynamic cortical networks of verbal and spatial working memory: effects of memory load and task practice

Working memory (WM), the ability to briefly retain and manipulate information in mind, is central to intelligent behavior. Here we take advantage of the high temporal resolution of electrophysiological measures to obtain a millisecond timescale view of the activity induced in distributed cortical networks by tasks that impose significant WM demands. We examined how these networks are affected by the type and amount of information to be remembered, and by the amount of task practice. Evoked potentials (EPs) were obtained from eight subjects performing spatial and verbal versions of a visual n-back WM task (n = 1, 2, 3) on each of three testing days. In well-trained subjects, WM tasks elicited transient responses reflecting different subcomponents of task processing, including transient (lasting 0.02-0.3 s) task-sensitive and load-sensitive EPs, as well as sustained responses (lasting 1-1.5 s), including the prestimulus Contingent Negative Variation (CNV), and post-stimulus frontal and parietal Slow Waves. The transient responses, with the exception of the P300, differed between the verbal and spatial task versions, and between trials with different response requirements. The P300 and the Slow Waves were not affected by task version but were affected by increased WM load. These results suggest that WM emerges from the formation of a dynamic cortical network linking task-specific processes with non-specific, capacity-limited, higher-order attentional processes. Practice effects on the EPs suggested that practice led to the development of a more effective cognitive strategy for dealing with lower-order aspects of task processing, but did not diminish demands made on higher order processes. Thus a simple WM task is shown to be composed of numerous elementary subsecond neural processes whose characteristics vary with type and amount of information being remembered, and amount of practice.     

Auditory and visual word processing studied with fMRI

Brain activations associated with semantic processing of visual and auditory words were investigated using functional magnetic resonance imaging (fMRI). For each form of word presentation, subjects performed two tasks: one semantic, and one nonsemantic. The semantic task was identical for both auditory and visual presentation: single words were presented and subjects determined whether the word was concrete or abstract. In the nonsemantic task for auditory words, subjects determined whether the word had one syllable or multiple syllables. In the nonsemantic task for visual words, subjects determined whether the word was presented in lower case or upper case. There was considerable overlap in where auditory and visual word semantic processing occurred. Visual and auditory semantic tasks both activated the left inferior frontal (BA 45), bilateral anterior prefrontal (BA 10, 46), and left premotor regions (BA 6) and anterior SMA (BA 6, 8). Left posterior temporal (middle temporal and fusiform gyrus) and predominantly right-sided cerebellar activations were observed during the auditory semantic task but were not above threshold during visual word presentation. The data, when averaged across subjects, did not show obligatory activation of left inferior frontal and temporal language areas during nonsemantic word tasks. Individual subjects showed differences in the activation of the inferior frontal region while performing the same task, even though they showed similar response latency and accuracy.     

Verbal exchange structure of brief psychodynamic-interpersonal and cognitive-behavioral psychotherapy.

A verbal exchange is a set of 2 people's co-occurring speech-act categories that accomplish some subtask within an interpersonal encounter. Factor analysis of verbal response mode (speech act) frequencies in 1,630 segments (each approximately 10 to 12 min) drawn from the brief psychodynamic-interpersonal or cognitive-behavioral treatment of 39 mainly depressed clients identified 6 exchanges in each treatment—4 that were the same in both treatments (Revealing, Storytelling, Explaining, and Inquiring) and 2 that distinguished each treatment (Exploring and Interpreting in psychodynamic–interpersonal treatment; Prescribing and Reframing in cognitive–behavioral treatment). The exchanges showed distinctive temporal patterns across segments of sessions and across sessions of each time-limited treatment. The verbal exchange is a midsize concept that links atomistic verbal codes with clinical or theoretical concepts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reliance on visual imagery and its relation to mental rotation

The relationship of habitual use of visual imagery and mental rotation was investigated. Reliance on Visual Imagery scores were used to define subjects as high frequency or low frequency visualizers. During the mental rotation task, subjects indicated if a pair of 2-dimensional stimulus figures displayed on a computer screen were identical or mirror-images. Figures on the right were rotated in relation to those on the left by 0, 60, 120, or 180 degrees. Data supported the prediction that subjects who report high use of imagery would perform the task with greater accuracy (z = 1.97, p < .05) than subjects who reported low use. The imagery groups did not differ in response latency (z = .91, p < .36). A comparison of performance on Trials 1 to 24 with performance on Trials 115-138 indicated a learning effect in both accuracy (z = 7.58, p < .01) and latency (z = 9.72, p < .01) for all subjects.     

Recency discrimination deficits in frontal lobe patients.

Damage to the frontal lobes appears to cause a deficit in the temporal organization of memory. M. P. McAndrews and B. Milner (see record 1992-16996-001) found that S-performed tasks (SPTs), which involve the performance of actions with common objects, allowed frontal-lobe-damaged patients to circumvent this deficit and perform normally on recency judgments. The present investigation of the critical properties of SPTs compared the performance of frontal-lobe-damaged patients and healthy controls on recency judgments under 5 encoding conditions: SPT, naming, visual imagery, experimenter-performed tasks, and verbal elaboration. Patients' performance varied across encoding conditions, but controls' did not. Post hoc comparisons confirmed that patients performed significantly worse than controls across all encoding tasks except SPT. The findings help elucidate the nature of both SPTs and memory for temporal order. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age-related deficits in generation and manipulation of mental images: I. The role of sensorimotor speed and working memory.

The authors investigated age-related slowing of information processing in mental imagery tasks. Eighty-five healthy adults (ages 18 to 77) performed a visual, sensorimotor, reaction-time task; a visual-perceptual choice reaction task; and 3 mental imagery tasks that varied in apparent difficulty and involved stimuli at 2 levels of graphic complexity. Age was associated with prolongation of response time across all tasks and both levels of stimulus complexity. Accuracy of response was adversely affected by increase in stimulus complexity in all tasks, whereas it was negatively related to age only on the tasks with substantial mental imagery requirements. Slowing of information processing and reduction in accuracy were mediated by declines in working memory but not by decrease of sensorimotor speed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nonexistent individual differences in reminiscence.

Proposes that there are no individual differences in reminiscence independent of the differences in level of performance on the motor task on which reminiscence is observed. Multivariate methods have failed to find such individual differences in reminiscence. Previous reports of relationships between reminiscence and organismic variables are explained as resulting from artifacts in the methods used. (23 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Shortening of atrioventricular interval improves ventricular filling and clinical outcome in patients with DDD pacemaker and left ventricular hypertrophy

This single case study of the ability to generate verbal and non-verbal imagery in a woman who sustained a gunshot wound to the brain reports a significant difficulty in generating images of word shapes but not a significant problem in generating object images. Further dissociation, however, was observed in her ability to generate images of living vs non-living material. She made more errors in imagery and factual information tasks for non-living items than for living items. This pattern contrasts with our previous report of the agnosic patient, M.S., who had severe difficulty in generating images of living material, whereas his ability to image the shape of words was comparable to that of normal control subjects. Furthermore, with regard to the generation of images of living compared with non-living material, M.S. shows more errors with living than nonliving items. In contrast, the present patient, S.M., made significantly more errors with non-living relative to living items. There appear to be two types of double dissociation which reinforce the growing evidence of dissociable impairments in the ability to generate images for different types of verbal and non-verbal material. Such dissociations, presumably related to sensory and cognitive processing demands, address the problem of the neural basis of imagery.     

Improvements in quadriceps strength with regular seated exercise in the institutionalized elderly

The quadriceps strength of a group of residents homes for the elderly (mean age 83 years) was assessed in a randomized controlled trial of seated group exercise versus group reminiscence therapy. Fifty-five of 65 volunteers completed the 6-month study, with 4 dropouts from the exercise group, and 6 dropouts from the reminiscence group. There were no adverse effects. Average of attendance at the exercise sessions was 72% (range, 18% to 98%) and 62% (range, 29% to 100%) at the reminiscence sessions. The reminiscence sessions comprised group interaction and discussion prompted by the use of reminiscence aids. By the end of the study, the change observed in the exercise group was significantly different from the reminiscence group in terms of quadriceps strength (p < 0.01, Mann-Whitney U test). Both groups improved equally in their ability to climb up steps, but neither cognitive function (Mini-Mental State Examination) nor reaction time altered significantly.     

Reminiscence and stage of illness in schizophrenia.

When given a repetitive inverse alphabet printing task to perform for 5 min. of massed practice, Early Stage schizophrenics (N=16) displayed a greater degree of improvement in performance (reminiscence) after a 2-min. rest than did Advanced Stage schizophrenics (N = 16). Early Stage and Advanced Stage schizophrenia were defined in terms of a theory of schizophrenia which postulates differential levels of arousal as characteristic of the stages of the disorder. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of mnemonic instructions on paired-associate recognition memory for faces or names.

96 undergraduates (4 experimental and 2 control groups) learned 2 lists of 10 pairs of number-faces or number-names. Experimental Ss learned the 2nd list under a mnemonic rhyme condition. 1/2 of the experimental Ss used imagery as a mediator while the remainder were given verbal mediation sets. Ss took longer to learn faces than names and longer to learn under mnemonic than control conditions. On recognition tests, faces evoked slower latency responses than names, whereas mnemonic sets, in particular imagery as opposed to verbal, reduced response time. Names were recognized better than faces, mnemonics improved recognition scores, and recognition of faces but not of names was facilitated by the mnemonics. Control-group data show that results are not attributable to practice effects. Questionnaire reports of learning strategies are also examined. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Receptive and expressive language activations for sentences: a PET study

Most language mapping studies have focussed on activations for single-word tasks. We examined activations for verbal auditory and generation tasks using sentence stimuli. [15O]-water PET was performed in 4 female and 5 male normal adults. Listening to sentences (minus rest) activated the superior and middle temporal gyri bilaterally, but mean activation was significantly stronger on the left. The strongest activation for sentence generation (minus repetition) was seen in the left middle and inferior frontal gyri (area 46). This focus appears to be anterior to activations reported for single-word generation, possibly due to greater verbal working memory demands of the sentential task. Additional activation of the left inferior temporal lobe can be attributed to lexicosemantic processing.     

Measurement of integrated sensory-motor function following brain damage by a computerized preview tracking task

A preview tracking task has been developed which has particular application to neurological assessment and rehabilitation. Generated and monitored by a graphic display computer, it permits accurate global quantification of the upper-limb sensory-motor system. The incorporation of 'preview' into the tracking task is considered to significantly increase its effectiveness and relevance in relation to normal daily activities. Applied to three groups of normal subjects, several features of normal psychomotor performance and learning were identified or verified: hand dominance is not significant in overall arm control; learning does not completely plateau; increase in age (15-59 years) results in only a minor overall decrement in performance; an initial wide performance distribution decreases dramatically in subsequent sessions. Applied to brain-damaged patients, particularly head injury or stroke, the preview tracking task allows assessment at regular intervals enabling sensory-motor recovery curves to be generated. The potential of this technique, to help determine the efficacy of therapeutic procedures on the recovery process, is illustrated with the presentation of results from three brain-damaged patients demonstrating zero, significant and disjointed recovery of sensory-motor function. The usefulness of the preview tracking task can be expanded by combination with a less frequently applied but more component specific neurological assessment battery.     

Bilingual aphasia: semantic organization, strategy use, and productivity in semantic verbal fluency

A semantic verbal fluency task (Animals, Foods) was administered to 16 aphasic, bilingual adults in French and English. Each subject was tested twice in each language. The two goals of the study were to compare performance across languages and to determine the effect of a deliberate grouping strategy on productivity. All subjects claimed approximately equal prestroke abilities in both languages. The number of words subjects produced was not significantly different in the two languages. Semantic organization across languages was also similar on Test 1. On Test 2, 8 subjects were instructed to group items by subcategory and 8 simply repeated the task. There was no consistent between-group difference in number of correct words or in the semantic organization of responses. Implications for the clinical use of verbal fluency tests and for further research into bilingual lexicosemantic systems are discussed.     

Verbal coding and display coding in the acquisition and retention of tracking skill.

120 Ss were trained on a pursuit tracking task with an irregular step-function input. Cues for coding the task were introduced via pretraining and rehearsal of a numerical code and by display overlays in a 2 X 2 X 3 design. 3 levels of specificity of cues were provided by the overlays with the most specific condition providing a numerical code like that of pretraining. The results showed that both pretraining and display coding facilitated early reduction of tracking error, but that neither these nor rehearsal of the numerical code affected retention performance after 1 wk. Taken together, these findings suggested that the verbal and display cues were used in the early coding of the task, but were less important later in practice and at retention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)