Université de Poitiers
Centre National de la Recherche Scientifique
Centre de Recherche Sur la Cognition et l’Apprentissage
Rapport technique : 2008/01/Y.BLA
Specificity of Practice: Interaction Between Concurrent Sensory Information and Terminal Feedback Yannick Blandin, Lucette Toussaint, Université de Poitiers et Charles H. Shea, Texas A&M University
A paraître dans / To appear in : Blandin, Y., Toussaint, L., & Shea, C. (2008). Specificity of practice : interaction between concurrent sensory information and terminal feedback. Journal of Experimental Psychology : Learning, Memory and Cognition.
Yannick Blandin and Lucette Toussaint, Centre de Recherches sur la Cognition et l’Apprentissage (UMR 6234), University of Poitiers, Poitiers, France; Charles H. Shea, Department of Health and Kinesiology, Texas A&M University. This study was supported by a grant from La Re´gion Poitou-Charentes (06/RPC-R-043) to Yannick Blandin. We are grateful to Alice F. Healy and Alan Salmoni for helpful comments concerning this article. We thank Jennifer Bordeaux, Attila Kovacs, and Melanie Krueger for help collecting the data. Correspondence concerning this article should be addressed to Yannick Blandin, Centre de Recherches sur la Cognition et l’Apprentissage, MSHS, 99 av., du Recteur Pineau, Poitiers, France, 86000. E-mail :
[email protected] 1
KEYWORDS: motor learning, specificity of practice hypothesis, sensory integration, visual and proprioceptive feedback, knowledge of results.
ABSTRACT In 2 experiments, the authors investigated a potential interaction involving the processing of concurrent feedback using design features from the specificity of practice literature and the processing of terminal feedback using a manipulation from the guidance hypothesis literature. In Experiment 1, participants produced (198 trials) flexion-extension movements to reproduce a specific pattern of displacement over time with or without vision of the limb position and with 100% or 33% knowledge of results (KR) frequency. The transfer test was performed without vision and KR. In Experiment 2, the authors assessed whether sensory information processing was modulated by the amount of practice. Participants performed 54 or 396 trials under a 100% or a 33% KR frequency with vision before being transferred to a no-vision condition without KR. Results of both experiments indicated that the Vision-33% condition suffered a larger detrimental effect of withdrawing visual information than the Vision-100% condition. Experiment 2 indicated that this detrimental effect increased with practice. These results indicated the reduction in terminal feedback prompted participants to more deeply process the concurrent visual information thus reinforcing their dependency on the visual information.
Since Woodworth’s experiment in 1899, the role played by sensory information in the learning and control processes guiding one’s action has been subjected to many debates. Two important contemporary theoretical accounts of the role of feedback in the learning of movements are the guidance hypothesis (Salmoni, Schmidt, & Walter, 1984), which focuses on the role of terminal feedback, and the specificity of practice hypothesis (Tremblay & Proteau, 1998), which focuses on concurrent feedback. Terminal feedback or knowledge of results (KR), information regarding the outcome of the movement, has been perceived as one of the most important variables in the learning of motor skills (Adams, 1971; Bilodeau & Bilodeau, 1958). The guidance hypothesis postulates that although frequent KR provided during practice guides the learner toward the correct response, it also leads to a dependency on KR and blocks the processing of important intrinsic information (Bjork, 1988; Schmidt, 1991). Support for the guidance hypothesis has come from experiments that have varied the amount (e.g., reduced KR frequency; Winstein & Schmidt, 1990) and format (e.g., summary; Schmidt, Young, Swinnen, & Shapiro, 1989; bandwidth; Lee & Carnahan, 1990) with which terminal feedback is presented during acquisition (see Wulf & Shea, 2004, for review). These experiments have shown that providing KR on every trial during acquisition (either with a 100% KR frequency or with a reduced bandwidth) enhances performance during acquisition but degrades the learning of a wide variety of tasks. The implication is that processing KR on every trial, although enhancing performance while the KR is present, results in reduced processing of other sources of information necessary to produce the movement when KR is withdrawn on retention and transfer tests. The specificity of practice hypothesis argues that early in practice participants determine the source(s) of sensory information that is (are) more likely to ensure optimal accuracy. Thereafter, participants process this source(s) of information to the detriment of all other sources of sensory information. Support for the specificity of practice hypothesis has been found in an increasing number of experimental results focusing on the errors produced on novision delayed transfer tests after vision has been used during acquisition and detailed analyses of movement kinematics (e.g., Khan, Elliott, Coull, Chua, & Lyons, 2002; Proteau, 2005; Proteau & Isabelle, 2002; Robin, Toussaint, Blandin, & Proteau, 2005), which allow a comparison of the impact of concurrent visual feedback on both central planning and feedback processing. For example, in the context of manual aiming, it has been reported that participants 2
very early in practice determine that vision of the movement is the optimal source of afferent information and proceed to process this information at the expense of other afferent sources. However, withdrawing visual information after its dominance has been established results in a detrimental effect on performance accuracy, providing support for the specificity hypothesis.
BRIEF REPORTS The purpose of these experiments was to investigate a potential interaction involving the processing of concurrent feedback using design features taken from the specificity of practice literature and the processing of terminal feedback using a manipulation taken from the guidance hypothesis literature. To date, the validity of the specificity of practice hypothesis has relied exclusively on experiments that have manipulated the constraints of the task (e.g., weak vision, target size, condition of practice), and typically the tasks used were discrete aiming tasks. Independently, research on the guidance hypothesis has focused on determining how manipulations of terminal feedback influence learning without regard to the processing of concurrent feedback. In this study, we wished to extend the validity of the specificity of practice hypothesis to movement pattern reproduction tasks practiced under 100% and 33% KR frequencies. Experiment 1 was designed to reproduce the classical specificity of practice effect and determine whether reduced KR frequency influences this effect. Experiment 2 was designed to assess whether sensory processing of visual information was modulated by both KR frequency and the amount of practice.
EXPERIMENT 1 In Experiment 1, we wanted to reproduce the classical specificity of practice results (i.e., a detrimental effect of withdrawal of vision on a delayed transfer test) and determine whether this effect is modulated by the processing of terminal feedback (100% or 33% KR frequency). During acquisition, participants were asked to produce flexion– extension movements with the left (nondominant) arm to produce a specific pattern of displacement over time. This movement pattern was produced during acquisition in either the proprioception _ vision (PV) condition or the proprioception (P) condition and with 100% or 33% KR frequency. A delayed transfer test (24 hr) was conducted in the P condition and without KR. According to the guidance hypothesis, groups that were provided with 100% KR should outperform groups that were provided with 33% KR during acquisition. According to the specificity of practice hypothesis, if vision is determined to be the optimal source of sensory information to ensure accuracy, then the PV condition should outperform the P condition regardless of the frequency of KR. A different pattern of results can be postulated for the transfer test. If providing participants with frequent KR during acquisition actually reduces the processing of intrinsic feedback, then the PV group with 33% KR should suffer a larger detrimental effect of withdrawing visual information than the PV group with 100% KR. This should be the case because the elimination of KR for some trials during acquisition should prompt participants to process the visual information more deeply, thus reinforcing their dependency on the visual cues. On the other hand, the P group with 33% KR should outperform the P group with 100% KR on the transfer test. Reducing KR frequency to 33% would be expected to force participants to increase their processing of proprioceptive information which in turn should enhance learning when compared to the 100% KR condition. In summary, manipulating both the sensory condition and the KR frequency in acquisition should produce a Sensory Condition _ KR Frequency interaction on the transfer test.
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METHOD Participants. Forty-one right-handed undergraduate students (M age _ 22 years, SD _ 3.2 years; 19 men and 22 women) participated in this experiment. Each participant completed an informed consent form prior to the experiment. Apparatus. The apparatus consisted of a horizontal lever supported at one end by a vertical axle that turned almost frictionlessly in a ball-bearing support. The support was fixed on the left side of a table, allowing the lever to move in the horizontal plane over the table. At the other end of the lever, a vertical handle was fixed (see Figure 1).
Figure 1. Top (top) and side view (bottom) illustrations of the participant’s position while performing the flexion– extension movement. The handle’s position could be adjusted so that when the participant grasped the handle, his or her elbow could be aligned with the axis of rotation. A potentiometer was attached to the lower end of the axis to record the position of the lever and its output was sampled at 450 Hz. A wooden cover was placed over the table to prevent participants from seeing the lever and their arm. The goal movement pattern, position of the lever, and the participants’ movement pattern could be projected onto the wall facing the participant, depending on the condition. Participants were seated approximately 2 m from the wall, and a 1.64-m _ 1.23-m image was projected on the wall. Task, experimental groups, and procedures. Participants were seated in front of the apparatus on an adjustable height chair so that the movement of their left upper arm was in a horizontal plane. In the starting position, the forearm lever was resting at a stop so that the upper arm–forearm angle was about 85°. Participants were asked to produce a sequence of extension–flexion movements to produce the spatial and temporal aspects of the goal pattern projected in front of them (see Figure 2 insert). 4
Figure 2. Root-mean-square error (RMSE) during acquisition and transfer for each experimental group in Experiment 1. Insert illustrates the goal movement pattern. P _ proprioception; V _ vision; 33 _ 33% knowledge of results; 100 _ 100% knowledge of results. The total goal pattern time was 1,500 ms (potentiometer output sampled for 2,000 ms). At the beginning of each trial, participants were asked to move the lever to the starting position. Approximately 1 s after the participant moved to the start position, a tone (50 ms in duration) indicated to him or her to perform the task when he or she was ready. As soon as the participant started moving, the goal movement pattern disappeared from the screen. Depending on the experimental condition, different information was provided to the participant both during and after the completion of a trial. In the PV condition, during the completion of the trial, a white cursor on a blue background indicated the lever’s actual position. In the P condition, the cursor indicating limb position was not presented. In both cases, participants were asked to reproduce the goal movement pattern as accurately as possible. After a 2-s interval, depending on the condition, KR was provided by superimposing the goal movement pattern (white) on the actual pattern produced (green). In addition, the root-mean-square error (RMSE) of the participant’s movement from the goal movement was calculated and displayed on the screen. The RMSE is the deviation of the actual pattern from the goal pattern calculated from movement onset over the first 1,500 ms. RMSE is sensitive to both response bias and within-participant variability. When presented, KR was displayed for 5 s. Participants were randomly assigned to one of four groups: PV–100% KR (n _ 10), PV–33% KR (n _ 10), P–100% KR (n _ 11), and P–33% KR (n _ 10). Participants performed 198 acquisition trials (22 blocks of 9 trials, with a rest period of 10 s between blocks). In the PV–100% KR condition, participants were provided concurrent visual information (white cursor) indicating the current position of the lever and proprioceptive information. Furthermore, at the end of each trial, KR was displayed on the screen. In the PV–33% KR condition, both the visual and proprioceptive information were 5
available, but KR was presented on only 3 trials for each acquisition block. For the P–100% KR condition, concurrent visual information indicating the lever’s position was not available during the trial, but KR was provided after each trial. Finally, for the P–33% KR condition, concurrent visual information indicating the lever’s position was not available during the trial, and KR was presented on 3 trials in each acquisition block. Approximately 24 hr after the completion of the acquisition session, participants performed a transfer test composed of 18 trials without vision of the lever position and KR.
RESULTS Mean RMSE during acquisition and transfer for the various groups are displayed in Figure 2. Acquisition. Acquisition data were submitted to a 2 (sensory condition: PV vs. P) x 2 (KR condition: 33% vs. 100%) x 22 (Blocks 1–22) analysis of variance (ANOVA) with repeated measures on block. The analysis revealed effects of sensory condition, F(1, 37) = 6.19, MSE = 655.38, p < .05, η2p = 0.14; KR condition, F(1, 37) = 18.92, MSE = 655.38, p < .05, η2p = 0.34; and block, F(21, 777) = 54.16, MSE = 123.5, p < .05, η2p = 0.59. RMSE for the PV conditions during acquisition was lower than for the P conditions. The analysis also indicated a KR Condition x Block interaction, F(21, 777) = 4.26, MSE = 123.5, p < .05, η2p = 0.11. Post hoc analysis (Newman–Keuls) indicated a beneficial effect of frequent (100%) KR on performance when compared with reduced (33%) KR frequency, especially at the beginning of acquisition (Blocks 1–4). Transfer. Transfer data were submitted to a 2 (sensory condition: PV vs. P) x 2 (KR condition: 33% vs. 100%) x 2 (Blocks 1 and 2) ANOVA with repeated measures on block. The analysis revealed an effect of sensory condition, F(1, 37) = 41.12, MSE = 719, p < .05, η2p = 0.53, and a Sensory Condition x KR Condition interaction, F(1, 37) = 6.86, MSE = 719.62, p < .05, η2p = 0.16. Post hoc analysis indicated that both the P–33% KR and the P–100% KR groups outperformed the PV– 100% KR and PV–33% KR groups. Furthermore, the PV–100% KR group outperformed the PV–33% KR group. No difference was found between the P–100% KR and P–33% KR groups.
DISCUSSION Results of the acquisition phase indicate that vision was an important source of sensory information used to improve acquisition performance. Note that the results of the transfer test clearly indicate that withdrawing visual information after its dominance has been established in the PV conditions produced a detrimental effect on performance accuracy when compared with the P conditions. These results indicate that the specificity of practice hypothesis, primarily based on results from manual aiming tasks, can be extended to a task in which a movement pattern has to be produced. In addition, the larger errors found in transfer for the PV–33% KR group when compared with the PV–100% KR group provide support for one of the primary predictions of the guidance hypothesis: Frequent KR provided during acquisition blocks the processing of important sensory information (visual information here), and on the other hand, reduced KR prompts participants to engage in additional processing of the visual information provided during the trial to intrinsically evaluate their own performance. Thus, deeper sensory information processing by the PV–33% KR group relative to the PV–100% KR group increased participants’ dependency on sensory information as demonstrated by the larger detrimental effect of suppressing visual information in transfer for the PV–33% KR group than for the PV–100% KR group. However, reducing KR frequency did not prompt participants in the P–33% KR condition to engage in additional processing of the proprioceptive information when compared with participants in the P–100% KR condition. In other words, although the effects were in the predicted direction, the detrimental effects typically associated with frequent KR were not found for the P condition. To our knowledge, this is the first direct empirical demonstration of the interactive, and perhaps counterintuitive, influences exerted by reduced frequency terminal feedback on the subsequent processing of concurrent feedback. That is, the processing of terminal feedback not only influences the planning of the next action (Wulf & Schmidt, 1994) but also modulates the processing of concurrent feedback needed for action control. 6
EXPERIMENT 2 In Experiment 2, we wanted to replicate, using a slightly more difficult task, the detrimental effect of withdrawal of visual information found in Experiment 1 and determine whether the amount of practice influences this effect. According to the specificity of practice hypothesis, withdrawing a source of sensory information that has been determined as important to ensure optimal performance (i.e., vision of the cursor in Experiment 1) should be less detrimental early in practice than later in practice. Indeed, many experiments have reported that the detrimental effects of vision withdrawal on performance can occur following a limited amount of practice if vision was identified as an important source of information very early in practice (Tremblay & Proteau, 1998). On the other hand, other results reported that the detrimental effect of vision withdrawal increases as a function of practice, indicating that concurrent feedback becomes increasingly important for motor control as expertise increases (e.g., Proteau, Marteniuk, Girouard, & Dugas, 1987; Yoshida, Cauraugh, & Chow, 2004). As in Experiment 1, we also wanted to assess whether sensory information processing was modulated by KR frequency, thus altering the magnitude of the detrimental effects of withdrawing vision in transfer. During acquisition in Experiment 2, participants were asked to reproduce the goal pattern movement for either 54 or 396 trials in either a PV–100% KR or a PV–33% KR condition before being transferred to a P condition without KR. As suggested by the results of Experiment 1, if a reduced KR frequency enhances the processing of the intrinsic visual feedback, then participants in the PV–33% KR condition should suffer a larger detrimental effect of withdrawing visual information than participants in the PV–100% KR condition. Furthermore, this detrimental effect should be larger after 396 trials than after 54 trials.
METHOD Participants. Forty-eight right-handed undergraduate students (M age = 22.9 years, SD = 3.3 years; 23 men and 25 women) participated in this study. Each participant completed an informed consent form prior to the experiment. Apparatus, task, and procedure. The apparatus was the same as the one used in Experiment 1. The goal pattern, however, included an additional reversal (see Figure 3 insert). Participants were randomly assigned to one of four groups (n = 12 per group): 396 trials–PV–100% KR, 396 trials–PV–33% KR, 54 trials–PV– 100% KR, or 54 trials–PV–33% KR. During the acquisition phase, participants performed 54 trials or 396 trials under a PV condition (same condition as PV in Experiment 1). For each practice condition, participants received either a 100% or a 33% KR frequency. Transfer was conducted as in Experiment 1.
RESULTS Mean RMSE during acquisition and transfer for the various groups are displayed in Figure 3.
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Figure 3. Root-mean-square error (RMSE) during acquisition and transfer for each experimental group in Experiment 2. Insert illustrates the goal movement pattern. P = proprioception; V = vision; 33 = 33% knowledge of results; 100 = 100% knowledge of results. Acquisition. Data collected during the first 54 trials of the acquisition phase for all groups were submitted to a 2 (amount of practice: 54 vs. 396 trials) x 2 (KR condition: 33% vs. 100%) x 6 (Blocks 1–6) ANOVA with repeated measures on block. The analysis revealed only an effect of block, F(5, 220) = 53.28, MSE = 153, p < .05, η2p = 0.55. Post hoc analysis (Newman– Keuls) indicated RMSE decreased progressively from Block 1 to subsequent blocks, larger error for Block 2 compared with all other blocks, larger error for Block 3 compared with Blocks 5 and 6, and larger error for Block 4 compared with Block 6. The analysis failed to indicate a significant effect of amount of practice, KR frequency, or any interactions. Data for the remaining 342 trials of the acquisition phase were submitted to a 2 (KR condition: 100% vs. 33%) x 38 (Blocks 7–44) ANOVA with repeated measures on block. The analysis revealed only an effect of block, F(37, 814) = 6.95, 2 MSE = 84.1, p < .05, ηp = 0.24. Post hoc analysis (Newman–Keuls) indicated RMSE continued to decrease from Block 7 to Block 11 ( p < .05) but remained stable for the following blocks. The analysis failed to indicate a significant effect of KR frequency or KR frequency x Block interaction. Transfer. Transfer data were submitted to a 2 (amount of practice: 54 vs. 396 trials) x 2 (KR condition: 33% vs. 100%) x 2 (Blocks 1–2) ANOVA with repeated measures on block. The analysis revealed an Amount of Practice x KR Condition interaction, F(1, 44) = 7.06, MSE = 1,231, p < .05, η2p = 0.14. The post hoc analysis indicated that following 396 acquisition trials, participants in the PV–100% KR group outperformed participants in the PV–33% KR group. On the other hand, following 54 acquisition trials, the analysis failed to indicate a difference between the PV–100% KR and PV–33% KR groups.
DISCUSSION 8
Our prediction based on the combined effects of the specificity of practice and reduced KR frequency was supported 1. The detrimental effect of withdrawing vision in transfer was larger for the PV–33% KR group after 396 trials compared with the PV–100% KR group after 396 trials. This suggests that the reduced KR frequency resulted in the participants engaging in deeper processing of the visual information in order to evaluate the response accuracy, which in turn reinforces their dependency on the visual cues. Therefore, the transfer results from Experiment 2 replicate those reported for Experiment 1. The results suggest that providing participants with frequent KR during acquisition blocks the processing of intrinsic visual feedback. Further, the processing of intrinsic feedback available during practice increased as the participants’ expertise increased.
GENERAL DISCUSSION In two experiments, we found consistent patterns of results supporting the specificity of practice hypothesis as formulated by Tremblay and Proteau (1998) and validated in numerous previous experiments (Adams, Goetz, & Marshall, 1972; Coull, Trembly, & Elliott, 2001; Ivens & Marteniuk, 1997; Proteau et al., 1987; Robin, Toussaint, Blandin, & Vinter, 2004; Robin et al., 2005; Soucy & Proteau, 2001; Yoshida et al., 2004). We also found KR frequency to modulate this effect such that frequent KR essentially blocked the processing of concurrent feedback reducing the detrimental effect of withdrawing vision on the transfer test. Until now, these two relatively independent literatures have separately chronicled the contribution of these forms of feedback (concurrent and terminal feedback), but the present results clearly demonstrate that an interaction exists between the manipulation of the concurrent and terminal feedback.
THE SPECIFICITY OF PRACTICE HYPOTHESIS We made several predictions on the basis of the specificity of practice hypothesis for the acquisition and transfer phases. First, we predicted that providing visual information during the acquisition phase (PV condition) would enhance performance when compared with the P condition and that removing visual information in a transfer test would cause a decrement in performance. The results of Experiment 1 indicate that vision of position of the performing limb, although via a cursor on the screen, allowed participants to reproduce the pattern of movement more accurately than participants in the P condition. Furthermore, results of both experiments indicate that participants in the PV conditions took advantage of the visual information of the ongoing limb movement to progressively decrease their errors, indicating that the use of vision was enhanced with practice. However, participants in the P condition were also able to learn to control their unseen limb via proprioception, resulting in improved performance during acquisition although the availability of vision was necessary for optimal performance. These results are important because they demonstrate that participants were able to use the available sensory information to enhance performance on the task. We predicted that removing visual information during the transfer test would result in a performance decrement. The results of the transfer test clearly indicate that withdrawing visual information produced detrimental effects on performance accuracy. This finding is important because it replicates the typical specificity of practice transfer results obtained previously for pointing tasks. Indeed, in Experiment 1, the RMSE values for the PV conditions in the transfer test suggest that what had been learned during acquisition was not transferable to the no-vision transfer test. Taken
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No beneficial effect of frequent KR was found during acquisition. However, the guidance hypothesis mainly relies on results obtained in the transfer test. In the present study, the Sensory Condition x KR Frequency interaction on the transfer test was the main prediction. Finally, in the literature, equivocal support for the guidance hypothesis in acquisition was reported (Wulf & Shea, 2004). 9
together, these results replicate the essential elements of the classical specificity of learning results obtained from experiments using pointing tasks (see Elliott, Helsen, & Chua, 2001; Proteau, 1992, for reviews). The results of the second experiment provide insight into the evolution of the role of visual information during the learning process. Our results indicate that reliance on vision of the ongoing limb position (when provided) was established from the beginning of practice and tended to remain stable with practice. Indeed, if we contrast the performance levels reached by participants in the PV–100% KR conditions at the end of practice (Blocks 6 and 44 following 54 and 396 trials, respectively) to the ones obtained in transfer, the detrimental effect of withdrawing vision remained relatively stable across the different amounts of practice. This conclusion was supported by a complementary analysis on the index of performance deterioration (IPD, Chicoine, Lassonde, & Proteau, 1992) computed for each group. To compute the IPD, the average RMSE obtained on the transfer test was first subtracted from the RMSE obtained for the last block of acquisition. This difference was divided by the RMSE from the last block of acquisition. This value indicates the proportional improvement (positive) or deterioration (negative) in performance from the end of practice to the transfer test. A low IPD value indicates stable performance from acquisition to transfer, whereas a large negative IPD value reveals performance deterioration from acquisition to transfer. Analysis failed to indicate a difference in the mean IPD value for the PV–100% KR group after 54 trials (-0.908) and the mean IDP value for the PV– 100% KR group (-0.889) after 396 trials, F(1, 44) = 0.003, MSE = 0.8259, p = .96, η2p = 0.00. Results of previous experiments, which used aiming tasks and contrasted the amount of practice during acquisition (Ivens & Marteniuk, 1997; Krigolson, Van Gyn, Tremblay, & Heath, 2006; Proteau et al., 1987; Proteau, Marteniuk, & Levesque, 1992; Proteau, Tremblay, & DeJaeger, 1998; Tremblay & Proteau, 1998), have found that withdrawing visual information in transfer produced a larger performance deterioration following extensive (more than 300 trials) than moderate (150 trials) or low practice (15 trials). Consequently, for both our task and aiming tasks, visual dominance was reported early in practice; however, contrary to the results found for aiming tasks, visual dominance did not appreciably increase with practice. This finding is consistent with the notion that with the type of task used in the present study, the role of proprioceptive information progressively increases with practice.
ROLE OF KR IN THE SPECIFICITY OF PRACTICE HYPOTHESIS The results of both experiments reveal that KR frequency provided to participants during acquisition modulated the processing of the sensory information available while they were performing a trial. Our results clearly indicate that providing participants with frequent KR during acquisition prompts participants to forgo the processing of intrinsic feedback on subsequent trials. Results of Experiment 1 suggest that when KR was reduced and both proprioceptive and visual information were available, participants engaged in deeper processing of the visual information than when KR was provided on all trials. This deeper processing reinforced their dependency on the visual cues as indicated by the detrimental effect of withdrawing vision on the transfer test. However, results of Experiment 2 indicate that this deeper sensory information processing when KR frequency was reduced was a function of amount of practice. That is, the detrimental effect of withdrawing vision after 396 acquisition trials was larger for the 33% KR groups than for the 100% KR groups, but no differences were found following only 54 acquisition trials. Although the RMSE decreased during acquisition, 54 trials were probably insufficient to develop a dependence on KR. On the other hand, the large detrimental effect of withdrawing vision after 396 trials indicated an increased processing of the visual information with practice, which in turn reinforces dependency on the visual information. This conclusion is supported by the complementary analysis performed on the IPD values. The analysis revealed significantly larger IPD values for the 396-trial group provided 33% KR (_1.852) compared with those obtained for the 100% KR groups following 396 trials (-0.889), F(1, 44) = 6.74, MSE = 0.8259, p < .05, η2p = 0.13. Results of transfer tests for both experiments indicate terminal feedback (KR) can be added to the numerous experimental factors that modulate the processing of concurrent sensory information. As proposed by the guidance 10
hypothesis (Salmoni et al., 1984), reduced frequency KR prompts participants to engage in deeper processing of the visual information in order to internally evaluate their response accuracy, which in turn reinforces their dependency on the visual cues. These results are consistent with the predictions of the guidance hypothesis.
SUMMARY Our results suggest that there is a potentially important interaction between the presentation of terminal feedback and the processing of the concurrent sensory information. This interaction occurs because reducing the frequency with which KR is presented increases the degree to which participants process visual information when it is available during practice, resulting in greater dependence on this information when it is withdrawn on retention or transfer tests.
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