Refining the continuous tracking paradigm to investigate implicit motor learning.

In two experiments we investigated factors that undermine conclusions about implicit motor learning in the continuous tracking paradigm. In Experiment 1, we constructed a practice phase in which all three segments of the waveform pattern were random, in order to examine whether tracking performance decreased as a consequence of time spent on task. Tracking error was lower in the first segment than in the middle segment and lower in the middle segment than in the final segment, indicating that tracking performance decreased as a function of increasing time-on-task. In Experiment 2, the waveform pattern presented in the middle segment was identical in each trial of practice. In a retention test, tracking performance on the repeated segment was superior to tracking performance on the random segments of the waveform. Furthermore, substitution of the repeated pattern with a random pattern (in a transfer test) resulted in a significantly increased tracking error. These findings imply that characteristics of the repeated pattern were learned. Crucially, tests of pattern recognition implied that participants were not explicitly aware of the presence of a recurring segment of waveform. Recommendations for refining the continuous tracking paradigm for implicit learning research are proposed.

Neural co-activation as a yardstick of implicit motor learning and the propensity for conscious control of movement.

Two studies examined EEG co-activation (coherence) between the verbal-analytical (T3) and motor planning (Fz) regions during a golf putting task. In Study 1, participants with a strong propensity to consciously monitor and control their movements, determined psychometrically by high scores on a movement specific Reinvestment Scale, displayed more alpha2 T3-Fz co-activation than participants with a weak propensity. In Study 2, participants who practiced a golf putting task implicitly (via an errorless learning protocol) displayed less alpha2 T3-Fz co-activation than those who practiced explicitly (by errorful learning). In addition, explicit but not implicit motor learners displayed more T3-Fz co-activation during golf putting under pressure, implying that verbal-analytical processing of putting movements increased under pressure. These findings provide neuropsychological evidence that supports claims that implicit motor learning can be used to limit movement specific reinvestment.

Probing the allocation of attention in implicit (motor) learning.

We investigated the attention demands associated with implicit and explicit (motor) learning and performance using a probe reaction time paradigm. Two groups of participants learned a golf putting task over eight blocks of 50 trials performed from different distances. One group (errorless learning) began putting from the shortest distance (25 cm) and moved progressively back to the furthest distance (200 cm). A second group (errorful learning) began putting from the furthest distance (200 cm) and moved progressively closer (25 cm). Retention tests were used to assess learning in the two conditions, followed by transfer tests in which participants used either an unusual putter or a very unusual putter. Transfer to the unusual putters had an equivalent effect on the performance of both errorless and errorful learners, but probe reaction times were unaffected in the errorless learners, suggesting that execution of their movements was associated with reduced attention demands. Reducing errors during initial learning trials may encourage an implicit mode of learning and lower the demand for cognitive resources in subsequent performance.

EEG activity during the verbal-cognitive stage of motor skill acquisition.

This study examined changes in EEG activity associated with motor performance during the verbal-cognitive stage of skill learning. Participants (n=14) were required to practice a sequential finger tapping task. EEG activity was recorded both before and after short-term practice, during finger tapping and during two control conditions. EEG power (Fz, Cz, Pz, T3, T4) and coherence (T3-Fz, T4-Fz, Fz-Cz, Fz-Pz) were computed for the theta (4-8 Hz), slow alpha (8-10 Hz), fast alpha (10-12 Hz), slow beta (12-20 Hz), and fast beta (20-28 Hz) bandwidths. Changes in motor performance were rapid during the very early stages of practice and then slowed in accord with the law of practice. These changes were accompanied by increases of theta power at Fz and beta coherence at T4-Fz, suggesting that progression through the verbal-cognitive stage of a sequential finger tapping task is accompanied by more narrowed attention and improved mapping between the stimuli and the finger movements.

Unsanctioned aggression in rugby union: relationships among aggressiveness, anger, athletic identity, and professionalization.

Aggressive players who intentionally cause injury to their opponents are common in many sports, particularly collision sports such as Rugby Union. Although some acts of aggression fall within the rules (sanctioned), others do not (unsanctioned), with the latter tending to be less acceptable than the former. This study attempts to identify characteristics of players who are more likely to employ unsanctioned methods in order to injure an opponent. Male Rugby Union players completed questionnaires assessing aggressiveness, anger, past aggression, professionalization, and athletic identity. Players were assigned to one of two groups based on self-reported past unsanctioned aggression. Results indicated that demographic variables (e.g., age, playing position, or level of play) were not predictive of group membership. Measures of aggressiveness and professionalization were significant predictors; high scores on both indicated a greater probability of reporting the use of unsanctioned aggressive force for the sole purpose of causing injury or pain. In addition, players who had been taught how to execute aggressive illegal plays without detection were also more likely to report using excessive force to injure an opponent. Results provide further support that highly professionalized players may be more likely to use methods outside the constitutive rules of Rugby Union in order to intentionally injure their opponents. Results are discussed within the context of the increasing win-at-all-cost attitude that is becoming more prevalent in sport and its implications for youth athletes.

Analogy versus explicit learning of a modified basketball shooting task: performance and kinematic outcomes.

The effects of differential instructional sets on motor skill acquisition were investigated using performance outcome and kinematic measures. Participants were provided with a single analogical instruction (analogy learning), a set of eight explicit (technical) instructions (explicit learning), or were not instructed (control). During a learning phase, participants (n=9 for each condition) performed a modified basketball shooting task over 3 days (160 trials per day). On the fourth day, participants performed a test phase consisting of two 40-trial retention tests, separated by a 40-trial secondary task transfer test, and completed a verbal protocol describing in detail the techniques that they had used to perform the task. No performance differences were found during the two retention tests, indicating similar amounts of learning for all groups. During the transfer test, performance deteriorated for both the explicit and control conditions, but not for the analogy condition. Participants in the analogy condition reported significantly fewer technical rules. Although no group differences were reported for kinematic variables, identification of movement components supported the claim that explicit learners exert conscious control over their movements, whereas analogy learners use a more implicit (unconscious or automatic) mode of movement control.

Reinvestment and falls in community-dwelling older adults.

BACKGROUND: Falls are common in older adults and have many adverse consequences. In an attempt to prevent further incidents, elder fallers may consciously monitor and control their movements. Ironically, conscious movement control may be one factor that contributes to disruption of automaticity of walking, increasing the likelihood of subsequent falls. OBJECTIVE: The Movement Specific Reinvestment Scale (MSRS), which aims to measure the propensity for movement-related self-consciousness and for conscious processing of movement, was used to try to discriminate elder fallers from non-fallers. METHODS: Fifty-two volunteer older adults, aged 65 or above, participated. In addition to the 10-item MSRS, participants completed the Mini-Mental State Examination questionnaire, Timed "Up & Go" test, and Four Word Short-Term Memory test. Demographics including age, gender, and history of falling were collected. RESULTS: Elder fallers scored significantly higher than non-fallers on both the movement self-consciousness and conscious motor processing components of the MSRS. Logistic regression revealed a significant association between the MSRS (conscious motor processing component) and "faller or non-faller" status. CONCLUSIONS: Elder fallers may have a higher propensity to consciously control their movements. The MSRS shows potential as a clinical tool with which to predict falls in the elderly, as well as to gain insight into the perception of safety during walking in any impaired patient.

Implicit motor learning and complex decision making in time-constrained environments.

The cost-effectiveness of the implicit (procedural) knowledge that supports motor expertise enables surprisingly efficient performance when a decision and an action must occur in close temporal proximity. The authors argue that if novices learn the motor component of performance implicitly rather than explicitly, then they will also be efficient when they make a decision and execute an action in close temporal proximity. Participants (N = 35) learned a table tennis shot implicitly or explicitly. The authors assessed participants' motor performance and movement kinematics under conditions that required a concurrent low-complexity decision or a concurrent high-complexity decision about where to direct each shot. Performance was disrupted only for participants who learned explicitly when they made high-complexity decisions but not when they made low-complexity decisions. The authors conclude that implicit motor learning encourages cognitively efficient motor control more than does explicit motor learning, which allows performance to remain stable when time constraints call for a complex decision in tandem with a motor action.

Implicit motor learning in surgery: implications for multi-tasking.

BACKGROUND: Implicitly learned motor skills are characterized by minimal conscious knowledge of the movements involved and stable performance despite stress, fatigue, or multi-tasking. In contrast, explicitly learned motor skills are characterized by conscious knowledge of the movements and performance that tends to be less stable under stress, fatigue, and multi-tasking. We examined the acquisition of a basic surgical skill in three observational learning treatment conditions designed to accomplish implicit or explicit motor learning. We then tested performance in conditions that emulated multi-tasking in the operating theater. Our intention was to elaborate current understanding of implicit and explicit processes that underpin observational learning in the surgical environment. METHODS: Thirty-six novice adults were assigned randomly to an observation-only, an instructed-observation, or a guided-observation treatment condition, in which they learned to perform a suturing and knot-tying task in a Learning Phase. Their performance during multi-tasking was then assessed objectively by motion analysis during a Test Phase. RESULTS: In the Learning Phase, performance improved equally in the treatment conditions throughout learning, with participants using fewer hand movements and completing the task more quickly. Participants in the observation-only and the guided-observation treatment condition, however, reported significantly less movement-related knowledge than participants in the instructed-observation condition. In the Test Phase, participants in the instructed-observation condition exhibited slower completion times and more hand movements when they were required to multi-task, whereas in the observation-only and the guided-observation treatment condition, participants showed stable performance. CONCLUSIONS: A surgical skill that is learned by observation alone or by observation accompanied by guidance to reduce the number of errors that are committed tends to be learned implicitly and to have stable performance during multi-tasking. The efficacy of observation for acquiring technical skills implies that, at least for some skills, verbal instructions may not be necessary.

Stable implicit motor processes despite aerobic locomotor fatigue.

Implicit processes almost certainly preceded explicit processes in our evolutionary history, so they are likely to be more resistant to disruption according to the principles of evolutionary biology [Reber, A. S. (1992). The cognitive unconscious: An evolutionary perspective. Consciousness and Cognition, 1, 93-133.]. Previous work (e.g., [Masters, R. S. W. (1992). Knowledge, (k)nerves and know-how: The role of explicit versus implicit knowledge in the breakdown of a complex motor skill under pressure. British Journal of Psychology, 83, 343-358.]) has shown that implicitly learned motor skills remain stable under psychological pressure and concurrent cognitive demands, and recently [Poolton, J. M., Masters, R. S. W., & Maxwell, J. P. (2007). Passing thoughts on the evolutionary stability of implicit motor behaviour: Performance retention under physiological fatigue. Consciousness and Cognition, 16(2), 456-468.] showed that they also remain stable under conditions of anaerobic fatigue that would have significantly challenged the survival skills of our ancestors. Here we examine the stability of an implicitly learned motor skill under fatigue conditions that primarily tax a different physiological system (the aerobic system), but which have equally strong evolutionary connotations. Participants acquired a throwing task by means of an errorless (implicit) learning method or an errorful (explicit) method. Motor performance in the errorless condition, but not the errorful condition, remained stable following an exhaustive VO2 max. running test. Our findings replicate and extend the work of Poolton et al., providing further support for Reber's evolutionary distinction between implicit and explicit processes.

Passing thoughts on the evolutionary stability of implicit motor behaviour: performance retention under physiological fatigue.

Heuristics of evolutionary biology (e.g., survival of the fittest) dictate that phylogenetically older processes are inherently more stable and resilient to disruption than younger processes. On the grounds that non-declarative behaviour emerged long before declarative behaviour, Reber (1992) argues that implicit (non-declarative) learning is supported by neural processes that are evolutionarily older than those supporting explicit learning. Reber suggested that implicit learning thus leads to performance that is more robust than explicit learning. Applying this evolutionary framework to motor performance, we examined whether implicit motor learning, relative to explicit motor learning, conferred motor output that was resilient to physiological fatigue and durable over time. In Part One of the study a fatigued state was induced by a double Wingate Anaerobic test protocol. Fatigue had no affect on performance of participants in the implicit condition; whereas, performance of participants in the explicit condition deteriorated significantly. In Part Two of the study a convenience sample of participants was recalled following a one-year hiatus. In both the implicit and the explicit condition retention of performance was seen and, contrary to the findings in Part One, so was resilience to fatigue. The resilient performance in the explicit condition after one year may have resulted from forgetting (the decay of declarative knowledge) or from consolidation of declarative knowledge as implicit memories. In either case, implicit processes were left to more effectively support motor performance.

Do undergraduate students' ratings of perceived aggression in sport reflect athletes' self-reported aggression? Comments on Pedersen (2007).

In 2007 Pedersen described the results of undergraduate students' ratings of 16 common sports based on their perceptions of the aggression in each sport. Unfortunately, it is unclear whether Pedersen's sample's perception of aggression actually reflects aggression of athletes who participate in these sports. Therefore, response of 1,441 British competitive athletes (817 men, mean age = 21.5, SD = 4.9) to a short aggression questionnaire were analysed to distinguish whether the same pattern of ranks reported by Pedersen could be replicated. In general, data were consistent with Pedersen's rankings (Correlations were moderate to high), but some exceptions were evident, particularly for male athletes.

Benefits of an external focus of attention: common coding or conscious processing?

We conducted two experiments to assess the effect attentional focus has on learning a complex motor skill and subsequent performance under secondary task loading. Participants in Experiment 1 learnt a golf putting task (300 practice trials) with a single instruction to either focus on their hands (internal focus) or the movement of the putter (external focus). No group differences were evident during learning or retention. Differences between the groups were only apparent under secondary task load; the external group's performance remained robust, while the internal group suffered a drop in performance. Verbal protocols demonstrated that the internal group accumulated significantly more internal knowledge and more task-relevant knowledge in general than the external group. Experiment 2 was designed to establish whether greater internal focus knowledge or greater explicit rule build up in general was responsible for performance breakdown. Two groups were presented with a set of six internal or external rules. Again, no performance differences were found during learning or retention. During the secondary task, both groups experienced performance deterioration. It was concluded that accumulation of explicit rules to guide performance was responsible for the internal group's breakdown in performance under secondary task loading and may be responsible for some of the performance differences reported previously.

The relationship between initial errorless learning conditions and subsequent performance.

This experiment explores a suggestion by [Maxwell, J.P., Masters, R.S.W., Kerr, E., Weedon, E. (2001). The implicit benefit of learning without errors. Quarterly Journal of Experimental Psychology A 54, 1049-1068] that an initial bout of implicit motor learning confers beneficial performance characteristics, such as robustness under secondary task loading, despite subsequent explicit learning. Participants acquired a complex motor skill (golf putting) over 400 trials. The environment was constrained early in learning to minimize performance error. It was predicted that in the absence of explicit instruction, reducing error would prevent hypothesis testing strategies and the concomitant accrual of declarative (explicit) knowledge, thereby reducing dependence on working memory resources. The effect of an additional cognitive task on putting performance was used to assess reliance on working memory. Putting performance of participants in the Implicit-Explicit condition was unaffected by the additional cognitive load, whereas the performance of Explicit participants deteriorated. The relationship between error correction and episodic verbal reports suggested that the explicit group were involved in more hypothesis testing behaviours than the Implicit-Explicit group early in learning. It was concluded that a constrained, uninstructed, environment early in learning, results in procedurally based motor output unencumbered by disadvantages associated with working memory control.

The role of working memory in motor learning and performance.

Three experiments explore the role of working memory in motor skill acquisition and performance. Traditional theories postulate that skill acquisition proceeds through stages of knowing, which are initially declarative but later procedural. The reported experiments challenge that view and support an independent, parallel processing model, which predicts that procedural and declarative knowledge can be acquired separately and that the former does not depend on the availability of working memory, whereas, the latter does. The behaviour of these two processes was manipulated by providing or withholding visual (and auditory) appraisal of outcome feedback. Withholding feedback was predicted to inhibit the use of working memory to appraise success and, thus, prevent the formation of declarative knowledge without affecting the accumulation of procedural knowledge. While the first experiment failed to support these predictions, the second and third experiments demonstrated that procedural and declarative knowledge can be acquired independently. It is suggested that the availability of working memory is crucial to motor performance only when the learner has come to rely on its use.

Drifting towards a diffuse control model of exploratory motor learning: A comparison of global and within-trial performance measures.

Accurate measurement is crucial for understanding the processes that underlie exploratory patterns in motor learning. Accordingly, measures of learning should be sensitive to the changes that take place during skill acquisition. Most studies, however, use trial-based global measures that assess performance but do not actually measure gradual changes taking place within trials. The present study attempted to remedy this shortcoming by analysing a visual adaptation task, and comparing traditional global measures of learning with new, within-trial measures. Movement time was the only global measure sensitive to changes in the movement trajectory during learning. Three new measures were expected to reveal changes to the movement trajectory that are associated with learning: (i) the length of runs, (ii) change of trajectory angle in relation to the target, and (iii) drift (change in distance from the target). All three measures were sensitive to learning and indicated a gradual straightening of the movement trajectories over trials. Furthermore, three different methods to partition trajectories into segments were examined. The new within-trial measures, irrespective of partitioning method, prove promising for the development of a diffuse control model of exploratory learning.

The implicit benefit of learning without errors.

Two studies examined whether the number of errors made in learning a motor skill, golf putting, differentially influences the adoption of a selective (explicit) or unselective (implicit) learning mode. Errorful learners were expected to adopt an explicit, hypothesis-testing strategy to correct errors during learning, thereby accruing a pool of verbalizable rules and exhibiting performance breakdown under dual-task conditions, characteristic of a selective mode of learning. Reducing errors during learning was predicted to minimize the involvement of explicit hypothesis testing leading to the adoption of an unselective mode of learning, distinguished by few verbalizable rules and robust performance under secondary task loading. Both studies supported these predictions. The golf putting performance of errorless learners in both studies was unaffected by the imposition of a secondary task load, whereas the performance of errorful learners deteriorated. Reducing errors during learning limited the number of error-correcting hypotheses tested by the learner, thereby reducing the contribution of explicit processing to skill acquisition. It was concluded that the reduction of errors during learning encourages the use of implicit, unselective learning processes, which confer insusceptibility to performance breakdown under distraction.

Antimalarial sulfide, sulfone, and sulfonamide trioxanes.

A series of trioxanes featuring sulfide, sulfone, and sulfonamide substituents in diverse positions has been prepared. Structure-activity relationship (SAR) generalizations highlight two major factors controlling the antimalarial potency of these new chemical entities: (1) the proximity of the sulfur-containing substituent to the crucial peroxide bond and (2) the oxidation state of the sulfur-containing substituent. Generally, sulfones are more antimalarially potent than the corresponding sulfides.

From novice to no know-how: a longitudinal study of implicit motor learning.

The aim of this study was to ascertain whether the performances of implicit and explicit learners would converge over an extended period of learning. Participants practised a complex motor skill--golf putting--for 3000 trials, either with a concurrent secondary, tone-counting task (implicit learning) or without such a task (explicit learning). The cognitive demands of the secondary task were predicted to prevent the accumulation of verbalizable rules about the motor task. The implicit group reported significantly fewer rules than the explicit group on subsequent verbal protocols. The performance of the implicit group remained below that of the explicit group throughout the learning phase. However, no significant differences were found between groups during a delayed retention test. Additionally, for the participants in the explicit group only, a Reinvestment Scale score correlated positively with the number of rules accrued and negatively with overall putting performance during the learning phase. We use the results to argue against the excessive use of verbal instruction during skill acquisition, which might be unnecessary and ultimately might hamper performance under stressful conditions.