Qualitative and quantitative change in the dynamics of motor learning

The experiments examined qualitative and quantitative changes in the dynamics of learning a novel motor skill (roller ball task) as a function of the manipulation of a control parameter (initial ball speed). The focus was on the relation between the rates of change in performance over practice time and the changing time scales of the evolving attractor dynamic. Results showed 3 different learning patterns to the changes in the dynamics as a function of practice that were mediated by the initial ball speed. Only participants who learned the task showed a bifurcation in coordination mode that was preceded by enhanced performance variability. The observed multiple time scales to motor learning are interpreted as the products of the dynamical stability and instability realized from (a) the continually evolving landscape dynamics due to bifurcations between attractor organization and (b) the transient phenomena associated with moving toward and away from fixed-point dynamics.     

Learning and performance effects of accurate and erroneous knowledge of results on time perception

Performance feedback (also known as knowledge of results or KR) has both performance and learning effects on many tasks. Earlier studies have demonstrated performance but not learning effects on time perception tasks. In this experiment, we dissociate and identify these two phenomena on two different time perception tasks. Participants were presented with either accurate (100%) or erroneous (80% or 120% of actual performance) KR on either a reproduction or a numerical estimation time perception task. Accurate (100%) KR reduced the group variability and increased the accuracy of response magnitude but left individual variability unchanged. Erroneous (80% or 120%) KR also reduced the group variability while leaving individual variation unchanged, but decreased the true accuracy of the response, with response magnitudes increasing for the 80% KR group and decreasing for the 120% group. Thus external KR that is in conflict with internal time cues overrides these internal cues and dictates response magnitude on these two tasks. Thus KR provides guidance for these behaviors. KR did not reduce the variability (dispersion) of participants' responses, but centered each participant's responses closer to the targeted performance. This decreased group response variability reflected a performance enhancing effect of KR because group response variability increased after KR was withdrawn. In contrast, response magnitudes remained changed for the duration of the post-KR period, indicating that KR also induced a learned response. Thus individual response variability, group response variability and response magnitude represent dissociable features of performance on these time perception tasks.     

Effects of training in rapid decoding on the reading comprehension of adult ESL learners

We report an experimental investigation of the effects on comprehension of increasing the decoding speed of three adult learners of English as a Second Language (ESL). Participants were taught to read lists of 25 difficult words in isolation until they could read the entire list at a mean rate of not more than 1.5 secs per word. They were then asked to read passages containing these words. Decoding speed and accuracy measures, for both the word lists and passages, and passage comprehension measures, were obtained. In a temporally contiguous within-subjects repeated trials reversal design, decoding training on isolated words was shown to be associated with significant increases in decoding speed and accuracy both in isolation and context, and improvements in the participants' comprehension. With all participants rate and accuracy gains in context were maintained in the final reversal phase, though the comprehension score gains did not. These results are discussed in terms of their implications for a decoding sufficiency hypothesis.     

Variable effects of a behavioral treatment package on the performance of inline roller speed skaters

We investigated the effects of a treatment package on the performance of correct relay tags with 4 inline speed skaters. The treatment package included verbal praise following correct tags, visual feedback of performance data, and instruction for improving performance. Initial gains in the frequency of correct tags were not maintained at 6-month follow-up when baselines were reestablished. Performance on the second intervention phase for the 3 original subjects was variable and differed from the initial phase, whereas the original findings were replicated in the 4th subject. Possible reasons for this variability and implications for future research and behavioral sport interventions are considered.     

There are stable individual differences in performance variability, both from moment to moment and from day to day

Individual differences in decision speed have been regarded as direct reflections of a "primitive" functional neurophysiological characteristic, which affects performance on all cognitive tasks and so may be regarded as the "biological basis of intelligence", or of age-related changes in mental abilities. More detailed analyses show that variability within an experimental session (WSV) is a stable individual difference characteristic and that mean choice reaction times (CRTs) are gross summary statistics that reflect variability, rather than maximum speed of performance. A total of 98 people aged from 60 to 80 years completed 36 weekly sessions on six different letter categorization tasks. After effects of practice and of circadian variability had been eliminated, individuals with lower scores on the Cattell Culture Fair intelligence test had slower CRTs and greater WSV on all tasks. A simulation study showed that the greater WSVs of low Cattell scorers led directly to the significantly greater variability of their mean CRTs from session to session. However because CRTs on tasks co-varied from session to session it was apparent that, besides being affected by WSV, individuals' between-session variabilities (BSVs) also vary because of state changes that affect their performance from day to day. It seems that both variability in performance from trial to trial during a session and variability in average performance from day to day are correlated, stable, individual difference characteristics that vary inversely with intelligence test performance. Methodological consequences of these results for interpretations of age-related cognitive changes, for variability between as well as within individuals, for individual differences in decision speed, and for circadian variability in performance are discussed.     

Individual differences in insular sensitivity during loss anticipation predict avoidance learning

The anterior insula has been implicated in both the experience and the anticipation of negative outcomes. Although individual differences in insular sensitivity have been associated with self-report measures of chronic anxiety, previous research has not examined whether individual differences in insular sensitivity predict learning to avoid aversive stimuli. In the present study, insular sensitivity was assessed as participants anticipated monetary losses while undergoing functional magnetic resonance imaging. We found that insular responsiveness to anticipated losses predicted participants' ability to learn to avoid losses (but not to approach gains) in a behavioral test several months later. These findings suggest that in addition to correlating with self-reported anxiety, heightened insular sensitivity may promote learning to avoid loss.     

Effects of feedback and calibration on the verbal estimation of the duration of tones

Two experiments investigated the effects of feedback (Experiment 1) and calibration (Experiment 2) on verbal estimation of the duration of tones ranging from 77 to 1183 ms in length. In Experiment 1, accurate feedback was provided after half the trials in the feedback condition, and this was contrasted with a no-feedback condition in which feedback was absent. In Experiment 2, in the calibration condition, participants estimated the duration of the second of two tones, after a first tone of a known duration (ranging from 50 to 1200 ms) had been presented. In the no calibration condition the value of the first tone was unknown. Compared with conditions without feedback or calibration, the feedback/calibration operation produced no significant change in group mean estimates, nor coefficients of variation of estimates, but the absolute deviation of estimates from the real stimulus duration, and the absolute deviation of individual estimates from the group mean, were both significantly reduced. The feedback/calibration thus made participants' mean estimates thus more accurate and more similar to one another, but the actual mechanism by which this was done was apparently a subtle process of adjustment, rather than a gross change in mean estimate or estimate variability.     

The Strategy-Specific Nature of Improvement: The Power Law Applies by Strategy Within Task

If strategy shifts speed up performance, learning curves should show discontinuities where such shifts occur. Relatively smooth curves appear consistently in the literature, however. To explore this incongruity, we examined learning when multiple strategies were used. We plotted power law learning curves for aggregated data from four mental arithmetic experiments and then plotted similar curves separately for each participant and strategy. We then evaluated the fits achieved by each group of curves. In all four experiments, plotting separately by strategy produced significantly better fits to individual participants' data than did plotting a single power function. We conclude that improvement of solution time is better explained by practice on a strategy rather than practice on a task, and that careful assessment of trial-by-trial changes in strategy can improve understanding of the effects of practice on learning.     

Absence of differences in the learning rate of a speed–accuracy movement task between women patients with mild and major depression and healthy adult women

This study tested the hypothesis that women patients with depression should perform movements more slowly and with greater variability, and their learning rate should be lower compared with age-matched healthy adult women. Three groups of adult women subjects (aged 33–37 years, women patients with mild and major depression and healthy adult women, n = 20 in each group) performed five series (20 repetitions in each series) of a speed–accuracy hand-movement task (SAT). The mean movement speed (V_a) of the SAT was lower and more stable (the coefficient of variation of V_a was lower) in women patients with major depression compared with those with minor depression and healthy adult women during the first series of the SAT. Only the V_a and movement accuracy (path of movement, S) of the SAT varied significantly in the five learning series regardless of the subject group (healthy women subjects and women patients with minor and major depression). The intraindividual variability of reaction time, V_a, maximal movement velocity to the target (tV_max), time to tV_max, and S did not change significantly in any of the groups. Our research data showed that although women patients with depression performed speed–accuracy movements more slowly, the stability of the performance of their movements and their learning rate did not differ from those of age-matched healthy adult women.     

Effects of decision-phase time constraints on emotion-based learning in the Iowa Gambling Task

Research employing the Iowa Gambling Task (IGT) has frequently shown that learning is impaired in various clinical populations. However, precisely what constitutes "unimpaired" control group learning remains unclear. In order to understand some of the possible factors underlying variability in control group IGT performance, the present study sought to manipulate features of the task to intentionally disrupt learning. Specifically, the present study investigated the effects of time constraints on emotion-based learning during automated administration of the IGT. For two groups of participants, a time-constraint of either 2-s or 4-s was implemented during the critical decision making period, while a control group received no time constraint. We also evaluated participants' subjective experience after every block of 20 trials. Results demonstrated that the 2-s group differed significantly from the control group. Subjective experience measures revealed rapid development of awareness of the advantageous and disadvantageous decks among all three groups. Overall, our findings demonstrate, for the first time, the effects of decision-phase time constraints on emotion-based learning and indicate that the IGT reward/punishment schedules are to some extent cognitively penetrable.     

Verbal knowledge, working memory, and processing speed as predictors of verbal learning in older adults

The present study aimed at modeling individual differences in a verbal learning task by means of a latent structured growth curve approach based on an exponential function that yielded 3 parameters: initial recall, learning rate, and asymptotic performance. Three cognitive variables-speed of information processing, verbal knowledge, working memory-and the participant's age were included in the model in order to explain individual differences in the learning parameters. The data come from the second wave of the Zurich Longitudinal Study on Cognitive Aging (D. Zimprich, Martin, et al., 2008) comprising 334 participants ranging in age from 66 to 81 years (M = 74.43, SD = 4.41). Among the logistic, the Gompertz, and the hyperbolic function, the exponential function described the data best. Reliable individual differences were found in all 3 learning parameters. The cognitive predictor variables affected the verbal learning parameters differentially: All 3 predictors affected positively initial recall, the asymptotic performance increased with better working memory and faster processing speed, and the learning rate was positively associated with verbal knowledge only. Age did not affect the learning parameters but correlated negatively with working memory and processing speed. The finding of large and reliable individual differences in learning is seen as evidence that the potential for positive change, or plasticity in adulthood is maintained and that it is worthwhile to enhance the determinants of learning or learning itself.     

A latent consolidation phase in auditory identification learning: time in the awake state is sufficient

Large gains in performance, evolving hours after practice has terminated, were reported in a number of visual and some motor learning tasks, as well as recently in an auditory nonverbal discrimination task. It was proposed that these gains reflect a latent phase of experience-triggered memory consolidation in human skill learning. It is not clear, however, whether and when delayed gains in performance evolve following training in an auditory verbal identification task. Here we show that normal-hearing young adults trained to identify consonant-vowel stimuli in increasing levels of background noise showed significant, robust, delayed gains in performance that became effective not earlier than 4 h post-training, with most participants improving at more than 6 h post-training. These gains were retained for over 6 mo. Moreover, although it has been recently argued that time including sleep, rather than time per se, is necessary for the evolution of delayed gains in human perceptual learning, our results show that 12 h post-training in the waking state were as effective as 12 h, including no less than 6 h night's sleep. Altogether, the results indicate, for the first time, the existence of a latent, hours-long, consolidation phase in a human auditory verbal learning task, which occurs even during the awake state.     

Individual Differences in Various Parameters of Motor Learning

60 Ss practiced 6 days on the stabilometer. No reminiscence or warm-up decrement was found; loss of skill occurred from 1-day layoffs which lessened as learning progressed. A 3-component exponential equation fitted the learning trend (including relearning). Both individual differences and intra-individual variations decreased exponentially with practice, but the ratio of individual differences to mean score increased. Practice had little influence on adjacent trial rs. Between scores in any particular pair of separated trials, r decreased when increasing number of trials separated them. Averaging 8 initial and 8 final trials gave optimum learning score reliability (r = .95). Individual rates of learning were not appreciably correlated with amounts of learning (r = .23). Final performance levels could only be predicted 50% from initial skill and cumulated amounts of learning unless more than half of the total practice (i.e., more than 90% of the potential learning) had been accomplished. The pattern of zero order rs between amount of learning and initial and final skill levels differed markedly from that previously observed in learning the ladder climb.     

Within-person variability in response speed as an indicator of cognitive impairment in older adults

Within-person variability may be an important indicator of central nervous system compromise. In this study, within-person variability in response speed was examined in community-dwelling older adults, ages 64-92 years, using a new framework that takes into account both the extent (single versus multiple domains affected) and nature (amnestic versus non-amnestic) of the cognitive impairment. Those with multiple domains of impairment were more variable than those who showed an isolated area of impairment, regardless of whether memory was one of the domains affected. Further, for those with difficulties in two or more non-memory domains, increased variability was most evident in more cognitively demanding situations, when individuals had to manipulate information held briefly in mind, switch cognitive set or inhibit an automatic response. Finally, group differentiation was better achieved when within-person variability as opposed to mean speed of performance was considered.     

How sequence learning creates explicit knowledge: the role of response–stimulus interval

Destrebecqz and Cleeremans (Psychon bull rev 8:343-350, 2001; Attention and implicit learning. John Benjamins Publishing Company, Amsterdam, pp 181-213, 2003) reported that increasing the response-stimulus interval (RSI) during incidental sequence learning improved participants' ability to discriminate old and new sequences in a recognition test. However, the original experimental design confounded RSI effects during training and test. I therefore repeated the experiment with an improved design in which RSI was varied systematically during the training phase and the recognition task. Participants learned a sequence of response locations either incidentally or intentionally. As a result, sequence recognition was not affected by the RSI manipulations in the group of incidental learners. With intentional learning instructions, recognition was unaffected by training RSI, but a long RSI in the test phase improved recognition performance over a short RSI. Response latencies while executing the test sequences indicated no effect of training RSI on sequence learning. However, sequence knowledge was expressed more readily when the RSI in the test phase matched the RSI in the training phase.     

The Effects of Text Structure Discrimination Training on the Writing Performance of Students with Learning Disabilities

The purpose of this study was to examine whether teaching three participants with learning disabilities to name and identify critical components (i.e., opening sentence, detail sentences, and key words) for four expository text structures, and to discriminate between well-written and poorly written components would improve their expository writing performance. After instruction, one participant immediately improved her expository paragraph writing skills. However, two participants needed additional instruction and feedback on their writing before their paragraph writing improved. Social validation of the study outcomes was assessed by comparing participants' paragraphs before and after instruction to paragraphs produced by same age peers without disabilities. After instruction, participants' paragraph scores were above the mean score of the normative comparison group. Implications for teaching writing skills to students with learning disabilities, and suggestions for future research are discussed.     

Children's initial sleep‐associated changes in motor skill are unrelated to long‐term skill levels

Sleep is considered to support the formation of skill memory. In juvenile but not adult song birds learning a tutor's song, a stronger initial deterioration of song performance over night‐sleep predicts better song performance in the long run. This and similar observations have stimulated the view of sleep supporting skill formation during development in an unsupervised off‐line learning process that, in the absence of external feedback, can initially also enhance inaccuracies in skill performance. Here we explored whether in children learning a motor sequence task, as in song‐learning juvenile birds, changes across sleep after initial practice predict performance levels achieved in the long run. The task was a serial reaction time task (SRTT) where subjects had to press buttons which were lighted up in a repeating eight‐element sequence as fast as possible. Twenty‐five children (8–12 years) practised the task in the evening before nocturnal sleep which was recorded polysomnographically. Retrieval was tested on the following morning and again 1 week later after daily training on the SRTT. As expected, changes in response speed over the initial night of sleep were negatively correlated with final performance speed after the 1‐week training. However, unlike in song birds, this correlation was driven by the baseline speed level achieved before sleep. Baseline‐corrected changes in speed or variability over the initial sleep period did not predict final performance on the trained SRTT sequence, or on different sequences introduced to assess generalization of the trained behaviour. The lack of correlation between initial sleep‐dependent changes and long‐term performance might reflect that the children were too experienced for the simple SRTT, possibly also favouring ceiling effects in performance. A consistent association found between sleep spindle activity and explicit sequence knowledge alternatively suggests that the expected correlation was masked by explicit memory systems interacting with skill memory formation.     

Dynamics of learning new postural patterns: influence on preexisting spontaneous behaviors

In stance, rotations around the hips and ankles typically exhibit a relative phase close to 20 degrees or 180 degrees . In 2 experiments, the authors studied the reciprocal influence of those coordination tendencies with learning an ankle-hip relative phase of 135 degrees . Before, during, and after learning a new mode of coordination, they assessed participants' (N = 24 in each experiment) spontaneous postural patterns with a tracking task in which no specific coordination was required. Learning the 135 degrees phase relation led to persistent modifications of the spontaneous in-phase and antiphase modes. Contrary to the theoretical predictions of the dynamical approach, the initial stability of the preexisting patterns did not influence the difficulty of producing the new mode or the improvement in performance during learning. Initial stability did, however, influence the rate and type of modification of spontaneous patterns. The authors discuss the results in relation to conclusions drawn from bimanual studies.     

Within-Person Variability in Response Speed as an Indicator of Cognitive Impairment in Older Adults

ABSTRACT

Within-person variability may be an important indicator of central nervous system compromise. In this study, within-person variability in response speed was examined in community-dwelling older adults, ages 64–92 years, using a new framework that takes into account both the extent (single versus multiple domains affected) and nature (amnestic versus non-amnestic) of the cognitive impairment. Those with multiple domains of impairment were more variable than those who showed an isolated area of impairment, regardless of whether memory was one of the domains affected. Further, for those with difficulties in two or more non-memory domains, increased variability was most evident in more cognitively demanding situations, when individuals had to manipulate information held briefly in mind, switch cognitive set or inhibit an automatic response. Finally, group differentiation was better achieved when within-person variability as opposed to mean speed of performance was considered.