آیا فواصل آزمون یادداری، نوع تمرین و میزان اطلاعات بازخوردی می تواند تحکیم حافظه حرکتی در سالمندان را تغییر دهد؟

Introduction

Age‑related cognitive decline affects multiple memory systems, with motor memory among the earliest to deteriorate. Motor memory consolidation— the stage most vulnerable to aging— relies on time‑dependent neural processes and is supported by factors such as sleep  Yet older adults often show reduced or absent consolidation gains compared with younger individuals. Practice structure is a key determinant of consolidation quality. Random practice typically enhances retention in younger adults, but findings in older adults are inconsistent, with some studies reporting benefits and others showing diminished consolidation (Dos Santos et al., 2014), implying age‑related variability in sensitivity to skill stabilization. Feedback frequency also influences consolidation, and delayed feedback appears advantageous in younger samples, although evidence in older adults is limited. Given these inconsistencies, it remains unclear whether specific combinations of practice structure and feedback frequency can produce distinct consolidation outcomes in aging populations. Addressing this gap may clarify mechanisms of motor memory decline and guide more effective instructional and rehabilitation strategies.

Methods

Seventy‑two older adults (36 women, 36 men; 60–70 years) residing in a nursing facility were recruited through purposive sampling. Eligibility required the absence of neurological, psychiatric, or major medical conditions and no use of substances affecting the central nervous system. Demographic characteristics, handedness, sleep quality, and cognitive status were assessed using standard questionnaires, and all sessions were conducted in the morning to control for circadian variation. Participants were randomly assigned to six experimental groups (n = 12), formed by crossing practice structure (constant vs. variable/random) with three frequencies of knowledge‑of‑results (KR) feedback (25%, 50%, 75%). Dart‑throwing served as the motor task, performed on a standardized electronic dartboard that automatically registered accuracy and error measures. Radial error was used as the primary performance index, with lower values indicating higher accuracy. The protocol included an acquisition phase followed by two retention tests. During acquisition, all groups completed eight blocks of 15 trials (120 total). Constant‑practice groups threw from a fixed distance, whereas variable‑practice groups practiced from three distances presented in random order. KR feedback was provided on the designated proportion of trials within each group and included information on error magnitude and direction. Participants were allowed to inspect the target after each attempt. Retention performance was assessed 30 minutes and 24 hours after acquisition through a single 15‑trial block with randomized distances identical across groups. Participants who did not complete both retention tests were excluded from analysis

Results

The results of the mixed ANOVA showed a significant main effect of assessment phase (p = 0.001), indicating that performance differed across the eighth acquisition block, the 30‑minute retention test, and the 24‑hour retention test. Comparison of means showed that participants had the lowest radial error (best performance) in the eighth acquisition block and the highest error in the 30‑minute retention test. A significant main effect of practice type was observed (p = 0.001), with the variable‑practice groups (M ≈ 3.85) showing better accuracy than the constant‑practice groups (M ≈ 4.26). The main effect of feedback frequency was also significant (p = 0.01), indicating that higher feedback frequencies during acquisition resulted in poorer retention performance. The interaction between assessment phase and practice type was significant (p = 0.001). Follow‑up tests showed that the variable‑practice / 25% feedback group had the lowest radial error in both the 30‑minute (M ≈ 3.81) and 24‑hour retention tests (M ≈ 3.44), while the constant‑practice / 75% feedback group showed the highest error values across retention tests (up to M ≈ 4.72). The interaction of practice × feedback and the three‑way interaction were not significant. Between-group analysis also showed no significant differences during acquisition (p = 0.80), while significant differences emerged at both retention intervals (p = 0.001).

Conclusion

The present study examined how practice structure and feedback frequency shape motor memory consolidation in older adults across two retention intervals (30 minutes and 24 hours). The findings showed that variable practice produced superior performance compared with constant practice in the randomized retention tests. Across both retention intervals, the variable‑practice group receiving 25% feedback demonstrated the most robust consolidation, whereas constant‑practice groups with 50% and 75% feedback showed the weakest performance at the 30‑minute interval. At the 24‑hour interval, all constant‑practice groups (25%, 50%, 75%) and the variable‑practice group with 75% feedback exhibited the lowest accuracy. These results align with evidence supporting the advantages of variable practice for long‑term retention  but contradict studies showing superior outcomes under constant practice , likely due to differences in task characteristics, participant age, and skill type. The superior performance under variable practice may reflect the richer encoding of motor information under high contextual interference, which promotes deeper processing, stronger retrieval demands, and more flexible skill adaptation. Repeated reconstruction of action plans across varied conditions enhances the stability and generalizability of motor memory.

Findings also support the benefits of reduced feedback frequency for consolidation, consistent with Travlos, Boroujeni et al  and schema theory Schmidt Lower feedback frequency encourages self‑evaluation, reliance on intrinsic cues, and greater cognitive engagement, which collectively foster more durable motor representations. Although some studies report opposite patterns, such discrepancies may stem from task demands and developmental differences in young vs. older adults.

Overall, reduced feedback and variable practice appear particularly beneficial for older adults, whose diminished sleep‑dependent consolidation mechanisms  may increase their reliance on enriched learning environments. These findings have practical implications for rehabilitation and motor‑skill instruction, highlighting the value of gradually reducing feedback and incorporating variability to enhance learning, independence, and long‑term retention

Footnotes

Ethical approval

This article is derived from the master’s thesis of Ms. Elham Khaksar from Alzahra University, Tehran.

Funding

This article has not received any financial support from any institution or organization.

Authors’ contribution

Study concept and design: P. Sh., P. H Analysis and interpretation of data: P. SH.,  M. H.; Drafting of the manuscript: E. Kh., M. H. Critical

Conflict of Interest

The authors of this article declare that they have no conflicts of interest.

Acknowledgements

We would like to express our sincere gratitude to all the participants who patiently took part in this research.