Influence of attentional focus on skilled motor performance: Performance decrement under unfamiliar focus conditions

Human Movement Science xxx (2013) xxx–xxx

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Influence of attentional focus on skilled motor performance: Performance decrement under unfamiliar focus conditions Heiko Maurer ⇑, Jörn Munzert Department of Psychology and Sport Science, University of Giessen, Germany

a r t i c l e

i n f o

Article history: Available online xxxx PsycINFO classification: 2330 2346 3270 Keywords: Attention Experience Level Familiarity Sports

a b s t r a c t Recent studies have demonstrated that the direction of attentional focus exerts a substantial influence on motor performance. We argue that in well-learned skills, this variable might be confounded with athletes’ familiarity with focus conditions. We studied the effect of familiarity and the direction of attentional focus on performance in two experiments using 2 (familiarity)  2 (direction) within-subject designs. A significant main effect of familiarity— that is, better performance under familiar compared with unfamiliar focus conditions—confirmed the influence of familiarity on motor performance. Results are consistent with existing concepts, but lead to different consequences when applied to sport and exercise. Ó 2013 Elsevier B.V. All rights reserved.

Psychological research reveals a strong interest in understanding the underlying processes that govern skilled motor performance (Ericsson, 2003). In recent years, numerous studies have demonstrated that directing attention during skill execution is a crucial factor for successful skilled performance (e.g., Beilock, Carr, MacMahon, & Starkes, 2002; Castaneda & Gray, 2007; Ford, Hodges, & Williams, 2005; Wulf, 2007a). One line of research concentrates on the direction of attentional focus by distinguishing between skill-focused (on any aspect of the motor action) versus environmental-focused attention (on environmental aspects that are not involved directly in skill execution) (e.g., Beilock, Bertenthal, McCoy, & Carr, 2004; Beilock et al., 2002; Ford et al., 2005; Gray, 2004). With reference to stage models of learn⇑ Corresponding author. Address: University of Giessen, Department of Psychology and Sport Science, Kugelberg 62, 35394 Giessen, Germany. Tel.: +49 641 9925233; fax: +49 641 9925239. E-mail address: [email protected] (H. Maurer). 0167-9457/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.humov.2013.02.001

Please cite this article in press as: Maurer, H., & Munzert, J. Influence of attentional focus on skilled motor performance: Performance decrement under unfamiliar focus conditions. Human Movement Science (2013), http:// dx.doi.org/10.1016/j.humov.2013.02.001

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ing (Anderson, 1993; Fitts & Posner, 1967; Schneider & Fisk, 1983), this approach assumes that the effects of attentional focus depend on skill level. In early learning phases, it is proposed that explicit cognitive processes are used to control actions in a step-by-step fashion. Hence, directing attention toward skill execution should be helpful for novices. With extended practice, however, the components of the skill become more and more proceduralized and can be executed in an automatic way without constant attentional monitoring (Anderson, 1993; Fitts & Posner, 1967). It is assumed that refocusing attention on proceduralized components can then hinder skilled performance by bringing these components back into working memory and decomposing them into smaller units (Beilock et al., 2002; Ford et al., 2005; Gray, 2004; Masters, 1992; Masters & Maxwell, 2008). This explanation for suboptimal performance in well-practiced motor skills has also been called the deautomatization-ofskills hypothesis (Ford et al., 2005). Assumptions based on the deautomatization-of-skills hypothesis have been confirmed using the dual-task paradigm. For example, Beilock et al. (2004, Experiment 1) examined novice and expert golfers’ putting performance under skill-focused and dual-task conditions. In the skill-focused condition, participants were instructed to monitor their swing and attempt to move their club head straight toward the target. In the dual-task condition, they putted while reacting to a series of tones designed to direct attention away from skill execution. As expected, the expert golfers were generally more accurate putters than the novices. Furthermore, novice putting was more accurate under skill-focused than under dual-task conditions, whereas experts showed the opposite pattern. Similar results have been reported for a soccer dribbling task (Beilock et al., 2002; Ford et al., 2005) and a simulated baseball batting task (Gray, 2004). For highly practiced skills, the deautomatization-of-skills hypothesis suggests that it is beneficial to focus on environmental aspects that are not involved directly in the online control of the movement (e.g., tones or word sequences in the above-mentioned studies). One conclusion for sports situations would be to focus attention on the audience or teammates, or even to try to think of extraneous information. However, another line of research suggests that it might be more beneficial to direct attention toward the effects of the movement on the environment. Studies in this field also address the direction of attentional focus, but they distinguish between an internal focus (on one’s own body movements) versus an external focus of attention (on the movement effects in the environment) (Wulf, 2007a; Wulf & Prinz, 2001). In terms of the deautomatization-of-skills hypothesis, an internal focus is always skillfocused, whereas an external focus can be either skill-focused or environmental-focused but is always a focus toward a movement-induced effect. Wulf and colleagues have performed numerous studies showing that an external effect-related focus of attention can enhance actual motor performance (see, for reviews, Wulf, 2007a,b). For example, expert golfers demonstrated greater pitch shot accuracy when instructed to use an external focus (on the pendulum-like motion of the club) compared with an internal focus (on the swing motion of the arms) (Wulf & Su, 2007, Experiment 2). This study directed attention toward skill execution in both the internal and external focus conditions. In contrast, attention can also be directed toward temporally and spatially more distal movement effects under external focus conditions (e.g., toward the trajectory of a ball or toward a target). Perkins-Ceccato, Passmore, and Lee (2003) as well as Wulf and Su (2007) have confirmed the external focus advantage for more distal external focus conditions as well. Wulf and colleagues formulated the constrained action hypothesis to explain the external focus advantage (McNevin, Shea, & Wulf, 2003; Wulf, 2007a). They assumed that using an external focus promotes a more automatic mode of movement control, whereas an internal focus constrains the motor system by intervening with ‘‘normal’’ control processes. They supported this view with empirical data on attentional capacity (Wulf, McNevin, & Shea, 2001), frequency of movement adaptations in balance tasks (McNevin et al., 2003), and muscular activity (Zachry, Wulf, Mercer, & Bezodis, 2005). Castaneda and Gray (2007) analyzed predictions regarding which focus condition increases the probability for successful performance based on both hypotheses (deautomatization-of-skills and constrained action) in a simulated baseball batting task performed by high- and low-skilled players. They confirmed the basic assumptions of both hypotheses. It is important to mention that the high-skilled players attained a higher batting performance when using an environmental-external focus (on the direction of the departing ball) compared to an environmental-irrelevant focus (on the frequency of a presented auditory tone). An environmental effect-related focus might be more beneficial than an Please cite this article in press as: Maurer, H., & Munzert, J. Influence of attentional focus on skilled motor performance: Performance decrement under unfamiliar focus conditions. Human Movement Science (2013), http:// dx.doi.org/10.1016/j.humov.2013.02.001

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environmental irrelevant focus, because it highlights the perceivable effects of the movement, and this might be more helpful when producing an appropriate action as suggested by Castaneda and Gray (2007) as well as Ford, Hodges, Huys, and Williams (2009) with reference to common coding theory (Prinz, 1990, 1997). A closer look at the assumptions proposed within the deautomatization-of-skills hypothesis reveals two possibly confounded variables—familiarity and direction of attentional focus. The basic idea within the approach is a deautomatization of highly practiced skills by directing attention toward movement execution (direction: toward skill execution), thus also directing attention toward aspects that athletes might normally no longer attend to (familiarity: low). In contrast, it is assumed that directing attention toward environmental aspects (direction: away from skill execution) does not disrupt proceduralized skill components and this is also what experts might normally do (familiarity: high). This raises the question whether the direction of attentional focus is the core variable responsible for the proceduralized skill components to either run uninterruptedly or be hampered. Frequently used attentional strategies might become integrated into the proceduralized skill components and thus no longer disruptive due to their familiarity. From this perspective, it would be interesting to see whether unfamiliar attentional focus conditions can cause a deautomatization of highly practiced skills irrespective of the direction of the attentional focus. A related variable—preference for using attentional focus strategies—has already been studied in some fairly recent experiments (Ehrlenspiel, Lieske, & Rübner, 2004; Marchant, Clough, Crawshaw, & Levy, 2009; Weiss, Reber, & Owen, 2008). The main result of these studies is that participants’ performance suffered when they preferred an external focus and were forced to switch to a nonpreferred internal focus. It is important to note that these experiments studied preference effects in less skilled participants, which clearly runs counter to our concept of familiarity in which highly practiced athletes develop very specific attentional strategies in proceduralized skills. Thus, the aim of the following two experiments is to clarify the effect of the variables direction and familiarity of attentional focus on skilled motor performance. 1. Experiment 1 A 2 (direction: skill-internal vs. environmental-external)  2 (familiarity: low vs. high) within-subject design was applied. Because we expected that highly practiced performers have acquired very specific individual attentional strategies (see, Gray, 2004), participants were asked to complete a questionnaire. This determined individually familiar and unfamiliar attentional foci by asking each player to specify which internal and external movement aspects they attend to often and which aspects they normally do not attend to. 1.1. Method 1.1.1. Participants Twenty-three female basketball players from the German junior national team participated and provided informed consent. All procedures were conducted according to the guidelines of the American Psychological Association. Participants were 14–18 years old (M = 16.30, SD = 1.29 years) and had several years of experience in competitive basketball (M = 7.85, SD = 2.16 years). The study was conducted within a national team training camp. 1.1.2. Attentional focus conditions Participants were asked to perform series of free throw shooting using different attentional foci (skill-internal/familiar, skill-internal/unfamiliar, environmental-external/familiar, and environmental-external/unfamiliar). To manipulate familiarity experimentally, we used the above-mentioned questionnaire to create individually familiar and unfamiliar focus conditions for each player. The questionnaire contained one list of skill-internal movement aspects and one list of environmental-external aspects specified by participants in a previous study who had been asked to report which aspects they directed their attention toward during free throw shooting (see Table 1 for the two lists of movement Please cite this article in press as: Maurer, H., & Munzert, J. Influence of attentional focus on skilled motor performance: Performance decrement under unfamiliar focus conditions. Human Movement Science (2013), http:// dx.doi.org/10.1016/j.humov.2013.02.001

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Table 1 Lists of skill-internal and environmental-external movement aspects used in Experiment 1. Familiar

Unfamiliar

Skill-internal

Straightening arm (6) Snapping wrist (6) Straightening legs (2) Fluent leg-arm coordination (7) Elbow under ball (1) Feeling ball’s weight (0) Weight on both feet⁄ (1)

Straightening arm (3) Snapping wrist (1) Straightening legs (2) Fluent leg-arm coordination (6) Elbow under ball (6) Feeling ball’s weight (5)

Environmental-external

Basket (5) Front part of rim (4) Middle of rim (6) Ball falling through basket (4) Ball flight trajectory (2) Highest point of ball flight (0) Rectangle of board (0) Back part of rim⁄ (2)

Basket (0) Front part of rim (3) Middle of rim (0) Ball falling through basket (2) Ball flight trajectory (3) Highest point of ball flight (5) Rectangle of board (10)

Note: The lists of skill-internal and environmental-external movement aspects were presented to the players with the questionnaire ascertaining individually familiar and unfamiliar focus conditions. The two aspects highlighted with ⁄ were added to the lists by players because they often attended to these aspects. The numbers of players selecting these aspects under the different conditions are given in parentheses.

aspects and the frequencies of selections). In order to specify familiar skill-internal and environmental-external focus conditions, we asked participants to choose one aspect they often attend to from each list. The lists could be extended if players did not find matching aspects, which was the case in three participants (see Table 1). The unfamiliar skill-internal and environmental-external focus conditions were specified by asking participants to choose one aspect from each list that they normally ignore. For each player, these four individually specified skill-internal and environmental-external movement aspects were used to generate the focus instructions within the four experimental conditions. Before performing the free throws under a specific attentional focus condition, players were given the following instructions: ‘‘Please focus your attention on [one of the four previously specified movement aspects] while performing the free throws in the following throwing series. Afterwards, you will be asked to rate how well you were able to implement this focus into your throwing movement.’’ 1.1.3. Procedure The experiment was conducted under standard free throw conditions on an indoor basketball court. Only one participant and the experimenters were on the court simultaneously. Players performed 20 free throws in each experimental condition. Performance was measured by counting the percentage of successful trials (i.e., ball passes through the basket irrespective of touching the rim or board) under each focus condition. After a warm-up series to accustom the players to the experimental setup, they completed the questionnaire for determining the different focus conditions. To prepare each of the subsequent four experimental conditions, they were instructed to direct their attention toward the specified aspect while performing their free throw shots. After each series, participants had to complete ratings on implementation quality and on the perceived impairment of the focus condition. They had to rate the ease of realization of the respective focus instructions on a 10-point scale ranging from 1 (very well) to 10 (not at all), and whether they felt disturbed in free throw shooting when focusing on the specified aspects on a 10-point scale ranging from 1 (not at all) to 10 (very strongly). These ratings were designed as a manipulation check and to ensure that participants complied with the focus instructions. The order of experimental conditions was varied systematically to control for sequence effects. Considering the number of participants, 23 out of 24 possible orders were used. At the end of the whole procedure, participants completed another questionnaire specifying their basketball experiPlease cite this article in press as: Maurer, H., & Munzert, J. Influence of attentional focus on skilled motor performance: Performance decrement under unfamiliar focus conditions. Human Movement Science (2013), http:// dx.doi.org/10.1016/j.humov.2013.02.001

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ence. Furthermore, they were asked whether they had a general preference in directing attention toward the throwing movement (e.g., toward the straightening of the arm—i.e., using a skill-internal focus) or toward effects of the movement (e.g., toward the ball flight—i.e., using an environmentalexternal focus of attention). 1.2. Results 1.2.1. Free-throw shooting performance Fig. 1 presents the mean percentage of successful shots in the different experimental conditions. Under familiar focus conditions, participants attained hit rates of 71.30% (skill-internal) and 67.83% (environmental-external); under unfamiliar focus conditions 65.65% (skill-internal) and 62.39% (environmental-external). Note that these hit rates confirm the high expertise of the participating athletes. A 2 (Familiarity)  2 (Direction) ANOVA with repeated measures revealed a significant main effect of familiarity, F(1, 22) = 5.12, p < .05, gp2 = .19, but no significant main effect for direction, F(1, 22) = 1.56, p = .23, gp2 = .07, and no significant familiarity  direction interaction, F(1, 22) < .01, p = .97, gp2 < .01. This result indicates better free-throw shooting performance under familiar focus conditions irrespective of focus direction. 1.2.2. Content of the focus conditions All participants were able to specify skill-internal and environmental-external movement aspects that they often attend to (familiar) and that they normally ignore (unfamiliar). Table 1 lists the specified aspects toward which players directed their attention within the four focus conditions (frequencies of selections are given in parentheses). It can be seen that not all of the movement aspects were chosen equally often under familiar and unfamiliar focus conditions. Means and standard errors of athletes’ ratings after the throwing series are reported in Table 2. Because a Kolmogorov-Smirnov test revealed that the ratings did not follow a normal distribution, they were analyzed with nonparametric methods based on the nonparametric marginal model (Brunner, Demhof, & Langer, 2002; Brunner & Puri, 2001). For the ease-of-realization rating, a 2 (Familiarity)  2 (Direction) analysis with repeated measures revealed a significant main effect of familiarity, F(1, 1) = 4.48, p < .05, suggesting that it was easier for participants to implement their familiar attentional strategies. No significant effects were found for direction, F(1, 1) = 2.10, p = .15, or for the familiarity  direction interaction, F(1, 1) = .33, p = .56. Similar results were found for the ratings of the players’ perceived interference of attentional foci with free throw shooting. They felt more impaired when using unfamiliar foci, as indicated by a significant main effect of familiarity, F(1, 1) = 15.93, p < .001. Again, no significant effects were found for direction, F(1, 1) = .43, p = .51, or for the familiarity  direction interaction, F(1, 1) = .80, p = .37.

Fig. 1. Mean percentage of successful throws out of a series of 20 shots under the four focus conditions. Error bars represent standard errors.

Please cite this article in press as: Maurer, H., & Munzert, J. Influence of attentional focus on skilled motor performance: Performance decrement under unfamiliar focus conditions. Human Movement Science (2013), http:// dx.doi.org/10.1016/j.humov.2013.02.001

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Table 2 Means and standard errors of players’ self-ratings on ease of realization of the specific attentional focus and on disturbance through the specific focus. Ease of realization

Skill-internal Environmental-external

Disturbance through focus

Familiar M (SE)

Unfamiliar M (SE)

Familiar M (SE)

Unfamiliar M (SE)

3.30 (0.37) 3.65 (0.48)

3.83 (0.38) 4.65 (0.48)

2.43 (0.33) 3.00 (0.46)

4.70 (0.43) 4.87 (0.60)

At the end of the experimental procedure, participants were asked whether they generally preferred skill-internal or environmental-external focus strategies. Eighteen players reported a preference for skill-internal attentional foci in free throw shooting; only five preferred environmentalexternal foci. 1.3. Discussion The main interest of Experiment 1 was in clarifying the role of the variables direction and familiarity of attentional focus on motor performance in highly practiced skills. Our results confirm the assumption that familiarity with attentional focus conditions influences the free throw performance of skilled basketball players. The participants’ ratings after the throwing series were consistent with the performance data. They were better at realizing their familiar attentional foci, and they felt more disturbed in throwing when focusing on unfamiliar aspects. However, ratings revealed neither a main effect of direction nor a significant interaction between direction and familiarity. Ratings on the self-perceived impairment due to the focus conditions cannot be interpreted directly as a measure for deautomatization. Furthermore, it is possible that participants’ ratings are influenced by their performance in the previous throwing series. Nonetheless, it is interesting to see that players did not feel more impaired in throwing under skill-internal focus conditions—as might have been expected on the basis of the deautomatization-of-skills hypothesis. However, creating individual focus conditions had two consequences that might hinder a clear interpretation of the familiarity effect. First, not all skill-internal and environmental-external focus instructions were used equally often under familiar and unfamiliar focus conditions. Second, one can argue that asking the players to specify their frequently used (familiar) and not frequently used (unfamiliar) attentional strategies might have raised players’ expectation to perform better under familiar conditions. Experiment 2 took these possible limitations into account. 2. Experiment 2 Experiment 2 was designed to replicate the results of Experiment 1 and to overcome possible methodological limitations resulting from studying familiarity effects in highly practiced athletes. In Experiment 2, familiarity with attentional focus conditions was generated in novices by learning a new motor task (golf putting) using standardized attentional foci. A 2 (familiarity)  2 (direction) within-subject design was applied, but familiarity with attentional focus conditions was generated. The chosen methodology allows a comparison of the same attentional foci under familiar and unfamiliar focus conditions. In addition, participants were not aware that familiar and unfamiliar focus conditions were being compared—as might have been the case in Experiment 1. 2.1. Method 2.1.1. Participants Fourteen golf novices (8 male, 6 female, Mage = 23.29 years, SDage = 2.67 years) were recruited as participants for Experiment 2. They provided signed informed consent before taking part in the experiment. Please cite this article in press as: Maurer, H., & Munzert, J. Influence of attentional focus on skilled motor performance: Performance decrement under unfamiliar focus conditions. Human Movement Science (2013), http:// dx.doi.org/10.1016/j.humov.2013.02.001

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2.1.2. Task and procedure Participants practiced a golf putting task on a carpeted indoor green (5 m  1.2 m) using a standard golf putter and ball. The ball was placed at a distance of 3.0 m from the center of the hole. The dependent variable was the percentage of successful trials in each test condition. The experiment involved two practice sessions and a separate test session conducted within one week. Each practice session consisted of 10 blocks of 15 trials; the test session contained 5 blocks of 30 trials. Regarding the total amount of 300 putts over the two practice sessions, participants can certainly not be expected to reach a degree of automatization and familiarity with attentional focus conditions similar to the highly practiced athletes in Experiment 1. Nonetheless, it seems plausible that deautomatization effects will occur after such amounts of practice, as indicated by results reported by Beilock and Carr (2001, Experiment 3) after a similar amount of practice in a putting task. To generate familiarity with a specific internal and external attentional focus during the practice sessions, participants were instructed to alternate between an internal and an external attentional focus in each successive block. Within the practice session, half of the participants used the focus instructions INT1 (‘‘Direct your attention toward the triangle formed by your arms and shoulders. It moves in a smooth and pendulum fashion.’’) and EXT1 (‘‘Direct your attention toward the movement of the club head. It moves on a virtual line between the ball and the middle of the hole.’’). The other half used the focus instructions INT2 (‘‘Direct your attention toward your wrists. They remain fixed while moving.’’) and EXT2 (‘‘Direct your attention to the movement of the club head. It continues moving toward the target after hitting the ball.’’). That way, the familiarity with the specific internal and external focus instructions was balanced between participants. Additionally, whether they started with the internal or external focus instruction in the first block of the practice phase was also balanced. After giving informed consent, participants were introduced to the putting task and their focus instructions. They were informed that they should direct their attention alternately toward two specific aspects while performing the task. Initially, they read the focus instructions attached to a poster board placed at a distance of 2.2 m from participants’ position while performing the putting task. They were asked whether they had a clear idea about which aspects they should attend to. Possible uncertainties were clarified verbally. Prior to the first putt of each block, participants were reminded of the instructions for that particular block. After each block, individuals had to rate the ease of realization of the respective focus condition on a 10-point scale ranging from 1 (very well) to 10 (not at all). The first block of the test session was used as a baseline condition. Participants were asked to perform the putts while doing a tone counting task to determine their putting performance independent of the specific attentional focus strategies. The tone counting task was designed similarly to the one used by Poolton, Maxwell, Masters, and Raab (2006). Low (200 Hz) and high (400 Hz) tones with a length of 300 ms were presented from a computer in random order and at random intervals with a mean length of 1200 ms (SD = 300 ms). Participants were asked to perform the putts as accurately as possible but also exactly count the tones irrespective of the tones’ pitch. Within the next four test blocks, participants were asked to use their two familiar and two unfamiliar internal and external focus conditions. To control for sequence effects, the order of the four focus conditions internal–familiar, internal–unfamiliar, external–familiar, and external–unfamiliar was varied, that is, 14 out of the 24 possible test orders were chosen randomly. 2.2. Results Again, participants performed better under familiar focus conditions, that is, they performed 39.29% (SE = 5.09%) and 38.81% (SE = 4.60%) successful trials under familiar internal and external focus conditions, and 36.67% (SE = 4.87%) and 33.10% (SE = 5.12%) successful trials under unfamiliar internal and external focus conditions. A 2 (familiarity)  2 (direction) ANOVA with repeated measures revealed a significant main effect for familiarity, F(1, 13) = 4.83, p < .05, gp2 = .27, but no significant main effect for direction, F(1, 13) = 1.06, p = .32, gp2 = .08, and no familiarity  direction interaction, F(1, 13) = .33, p = .57, gp2 = .03. An additional 2 (familiarity)  2 (direction)  2 (instruction) ANOVA was used to control whether the result pattern depended on the specific focus instructions (i.e., whether instructions INT1 and EXT1 had a different effect on performance than INT2 and EXT2). This was Please cite this article in press as: Maurer, H., & Munzert, J. Influence of attentional focus on skilled motor performance: Performance decrement under unfamiliar focus conditions. Human Movement Science (2013), http:// dx.doi.org/10.1016/j.humov.2013.02.001

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not the case, because neither a significant instruction effect nor a two-way or three-way interaction effect with the variable instruction was found as indicated by F values <1.0 for all effects. A one-way ANOVA with repeated measures and a priori contrasts was used to compare the results of the four attentional focus conditions with the performance in the baseline condition. Whereas participants performed significantly better when using familiar attentional foci (internal: F(1, 13) = 4.69, p < .05, gp2 = .27, external: F(1, 13) = 9.36, p < .01, gp2 = .42) than under the baseline condition, there were no significant differences between performance under unfamiliar focus conditions (internal: F(1, 13) = 2.28, p = .16, gp2 = .15, external: F(1, 13) = .48, p = .50, gp2 = .04) and the baseline. For the participants’ ease-of-realization ratings, a 2 (Familiarity)  2 (Direction) ANOVA with repeated measures did not reveal any significant statistical results for familiarity: F(1, 13) = 1.68, p = .22, gp2 = .12, direction: F(1, 13) = .11, p = .75, gp2 < .01, or familiarity  direction: F(1, 13) = .94, p = .35, gp2 = .07. 2.3. Discussion Experiment 2 was designed to replicate the results of Experiment 1 using a different operationalization of familiarity with attentional focus conditions. In contrast to Experiment 1, participants were not asked to specify familiar and unfamiliar focus conditions but had to practice under specific internal and external instructions before switching to unfamiliar internal and external instructions. Exactly the same pattern of results was found in Experiment 2 as in Experiment 1, that is, a main effect of familiarity indicating better performance under familiar focus conditions. In Experiment 2, an additional baseline condition was introduced using a tone counting task while putting to prevent participants using specific attentional foci. Whereas there was no difference between performance in the baseline condition and the unfamiliar focus conditions, putting performance was significantly better under familiar compared to the baseline condition. These results fit in well with the assumption that frequently used familiar focus strategies become integrated into the proceduralized skill components and are no longer disruptive to skill execution. Using the unfamiliar focus conditions, however, might have introduced some additional cognitive load similar to the tone counting task resulting in lower performance. This can be interpreted as less automated skill execution. 3. Discussion The main interest in the present experiments was to gain more detailed insights into the mechanisms of attentional processes that influence skilled motor performance. The deautomatization-ofskills hypothesis suggests that directing attention toward the execution of highly practiced skills can cause a deautomatization of proceduralized skill components and thereby disrupt performance (Beilock et al., 2002; Ford et al., 2005; Gray, 2004). We argue that the variables direction and familiarity of attentional focus might be confounded, and that it is not clear whether a change in the direction of attentional focus (environmental to skill-focused) is responsible for disrupting proceduralized skill components, or whether it is the switch from a familiar to an unfamiliar attentional strategy that decreases performance. Frequently used attentional strategies may become integrated parts of the skill and no longer impact on automated skill execution. Hence, we suggest that familiarity with attentional focus conditions might be a more critical variable for disrupting proceduralized motor skills than the direction of attentional focus. The influence of familiarity with attentional focus conditions was studied in two experiments. In Experiment 1 highly skilled young basketball players were asked to perform free throw shooting while focusing their attention on the skill-internal and environmental-external aspects they often attend to (familiar condition) and to aspects they normally ignore (unfamiliar condition). Questionnaires were used to ascertain the attentional strategies of participants and to subsequently generate individually familiar and unfamiliar focus conditions. As hypothesized, players performed better under familiar focus conditions. However, a potential drawback of this experiment is that players might have been influenced by the a priori questionnaire about their familiar and unfamiliar foci. In Experiment 2, we prevented this by using novices who were blind to the focus on familiarity. That is, they were inPlease cite this article in press as: Maurer, H., & Munzert, J. Influence of attentional focus on skilled motor performance: Performance decrement under unfamiliar focus conditions. Human Movement Science (2013), http:// dx.doi.org/10.1016/j.humov.2013.02.001

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structed to use internal and external focus conditions in practicing golf putting over two days. This meant that familiarity was generated rather than assessed. In a test session, they putted under these familiar focus conditions and under additional unfamiliar conditions. Again, participants performed significantly better under familiar focus conditions. In both experiments, we found no effect of direction of attentional focus instructions. Due to the well-documented external focus advantage we are hesitant to argue that direction of attentional focus does not have any influence on skilled motor performance. In Experiment 1, there might have been two reasons for the missing direction effect. First, most players (18 out of 23) reported a general preference for focusing their attention toward the free throw shooting movement, and this may well advantage performance under these focus conditions. Second, because participants used individualized focus instructions, they focused their attention on very different aspects within the skill-internal and environmental-external focus conditions, and not all of them might be equally helpful for performing the task. In Experiment 2, participants were familiarized with internal and external focus conditions within the practice phase. This design differs from those in other experiments studying the effects of internal and external attentional focus conditions, thereby making a direct comparison of the internal/external effect difficult. Furthermore, it has to be pointed out that the methodology of the present experiments differs from that used in most studies addressing the deautomatization-of-skills hypothesis. Whereas these studies used secondary tasks to direct attention toward skill execution or toward task-irrelevant environmental aspects (e.g., Beilock et al., 2002; Gray, 2004), we used instructions to direct the players’ attention toward either skill-internal or environmental-external movement aspects. These differences prevent any direct comparison of results. Nonetheless, the present findings are compatible with existing data and the deautomatization-of-skills hypothesis (Ford et al., 2005). The basic idea of the deautomatization-of-skills hypothesis is that proceduralized skill components are disrupted by directing attention toward aspects that athletes normally no longer attend to—that is, by using an unfamiliar attentional focus. Many expert athletes may normally direct their attention toward environmental aspects such as the position of teammates or the final effect of a task (Ford et al., 2009), so that focusing on the skill execution might also be an unfamiliar attentional focus for them. Recent results (Wulf, 2008) are in line with these considerations. Wulf studied the effects of attentional focus conditions in balance acrobats performing a balance task (standing on an inflated rubber disk). While there were no differences between internal (‘‘focus on minimizing movements of your feet’’) and external (‘‘focus on minimizing movements of the disc’’) focus instructions, participants showed higher frequencies of movement adaptations in the control condition when they were free to adopt their ‘‘normal’’ focus of attention. In line with our assumptions, one might expect that the balance experts developed very specific attentional strategies over years of practice, and it can be supposed that they used these familiar focus conditions in the control condition. Hence, the suggested role of familiarity is a specification of the causation of the deautomatization of skilled performance and not a new explanation of how skilled performance can be impaired by attentional processes. However, when it comes to making possible recommendations for athletes’ attentional strategies, consequences differ quite considerably: If direction were to be the central variable, then one would recommend athletes to avoid focusing on skill-internal aspects and direct their attention toward environmental-external aspects. In contrast, if familiarity were central, one would advise them to use familiar focus strategies, and one suitable focus strategy would also be to focus on skill-internal movement aspects. At this point, it should be emphasized that using a preferred and familiar attentional focus condition does not necessarily have to be the most beneficial approach, as indicated in results reported by Stoate and Wulf (2011) and Wulf, Shea, and Park (2001). For instance, Wulf et al. (2001) found better performance under external focus conditions in a balance task irrespective of players’ preference for internal and external focus instructions. Participants in this study, however, were novices, and their familiarity with the specific focus conditions was low. In contrast, results from Wulf (2008) with balance acrobats indicate an effect of familiarity. Hence, familiarity with attentional focus conditions might be of higher relevance in skilled performance, which is in line with the assumptions of the deautomatization-of-skills hypothesis. We hypothesized that familiar attentional focus conditions would not negatively impact on movement execution because such frequently used attentional foci might become integrated parts of proPlease cite this article in press as: Maurer, H., & Munzert, J. Influence of attentional focus on skilled motor performance: Performance decrement under unfamiliar focus conditions. Human Movement Science (2013), http:// dx.doi.org/10.1016/j.humov.2013.02.001

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ceduralized skill execution. Now we would like to discuss our results on the level of underlying motor control processes since this might help to specify how such a deautomatization of proceduralized motor skills impacts on motor execution and provokes performance breakdowns. Two recent findings are important in this regard. First, it has been repeatedly demonstrated that focusing attention toward movement execution results in increased muscular co-contraction compared to an external focus of attention. This was found in force production tasks (e.g., Lohse & Sherwood, 2012; Vance, Wulf, Töllner, McNevin, & Mercer, 2004) as well as in complex sports skills as basketball free throw shooting (Hossner & Ehrlenspiel, 2010; Zachry et al., 2005). Such an increase in muscular stiffness is commonly interpreted as ‘‘freezing degrees of freedom’’ with reference to Bernstein (1967), that is, a strategy to enlarge control in movement execution. Second, Hossner and Ehrlenspiel (2010) showed that the increased muscular co-contraction is accompanied by a reduction of compensatory variability which can be a reason for degraded performance in goal oriented tasks (Müller & Sternad, 2004). Let us now consider the familiarity effect. Muscular co-contraction can also be expected here. Using an unfamiliar focus regardless of direction should be a situation with increased uncertainty for a person—how will the unfamiliar focus impact on movement execution and performance? Hence, one might expect that this situation induces the attempt to control the movement in more detail resulting in a general increase in muscular stiffness. Combined with the result of reduced compensatory variability when muscular cocontraction increases, this might lead to performance decrements and can be an explanation for our result on the motor control level. Summarizing these considerations, a motor control perspective accompanied by analyzing physiological and kinematic measures of movement execution can fruitfully extend research on the effects of attentional focus. This would also allow capturing changes in movement planning and execution which do not necessarily have to be reflected in motor performance. The results of the present experiments demonstrate how familiarity with attentional focus conditions has a considerable impact on motor performance. This has important consequences not only for the theoretical concepts about directing attention in motor skill execution but also for the formulation of recommendations for competitive settings in sports.

Acknowledgement This research was supported by grants from the German National Institute for Sport Sciences under reference number 07/10/68/04 and 07/10/04/05.

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Please cite this article in press as: Maurer, H., & Munzert, J. Influence of attentional focus on skilled motor performance: Performance decrement under unfamiliar focus conditions. Human Movement Science (2013), http:// dx.doi.org/10.1016/j.humov.2013.02.001