The Role of Enactment in Learning American Sign Language in Younger and Older Adults

“Tell me, and I will forget. Show me, and I may remember. Involve me, and I will understand” (Confucius, 450 B.C). Philosophers and scientists alike have pondered the question of themind-body link for centuries. Recently the role ofmotor information has been examined more speci�cally for a role in learning and memory. is paper describes a study using an errorless learning protocol to teach characters to young and older persons in American Sign Language. Participants were assigned to one of two groups: recognition (visually recognizing signs) or enactment (physically creating signs). Number of signs recalled and rate of forgetting were compared between groups and across age cohorts. ere were no signi�cant differences, within either the younger or older groups for number of items recalled. ere were signi�cant differences between recognition and enactment groups for rate of forgetting, within young and old, suggesting that enactment improves the strength of memory for items learned, regardless of age.


Introduction
A growing volume of research is dedicated to understanding the role of physical engagement in learning, memory, and retrieval; however, this is by no means a new �eld of inquiry. Herman Ebbinghaus [1], a pioneer in the study of learning and memory, proposed a model that plotted the rate of forgetting and the factors that in�uenced the process of forgetting. Memory strength was dependent on two factors in his model: memory representation and active recall. Memory representation can be improved through environmental enrichment, which involved adding sight, sound, scent and tactile input to enhance the memory representation for an item. Active recall, or spaced repetition, improves memory strength by increasing time between recall so that the memory trace is being strengthened with each recall attempt [2,3].
Environmental enrichment, the �rst component of Ebbinghaus's memory strength model, can include visual, auditory, olfactory, and tactile stimulation to engage multimodal processing. Enactment engages tactile and kinesthetic feedback by pairing a physical activity or movement to an item to be remembered. Research has consistently shown that enactment of verbal items provides enhanced memory performance compared to traditional verbal recall tasks [4]. An example of enactment of verbal items would be bringing your hand to your mouth to mime eating, when the spoon or fork is the verbal item to be remembered.
ere are four main theories in the literature proposed to explain the enactment effect (also referred to as the subject performed task (SPT) effect). One theory, proposed by Cohen and Bean [5], suggests that the enactment effect is automatic and nonstrategic. Evidence exists that traditional strategic learning effects, found in verbal recall tasks, are not found when examining enactment [6]. Another theory [7,8], suggests that the enactment effect is partially automatic and derives its bene�t from the multimodal engagement that occurs during enactment, including visual, auditory, and tactile stimulation [6]. A third theory proposes that enactment encoding is organized into independent visual, auditory and motor programs, with the motoric being the most efficient, evidenced by the enactment effect [9]. Finally, a fourth theory contradicts the nonstrategic proposal of Cohen by suggesting that the enactment effect is entirely due to self-involvement and experiential registration, or episodic encoding of a personal experience [10].
e Cohen and Backman/Nilsson theories have converged in light of recent data. A revised view is that the nonstrategic nature of enactment is maintained with the spec-i�cation of physical movement and multimodality encoding as critical components [6]. Several experiments have demonstrated an enactment effect, although the interpretation of the cause of this improvement remains controversial [11].
e second component of Ebbinghaus' model of memory is active recall. Active recall can improve memory strength through spacing, repetition, and timing. Manipulating the interval between study and recall, for example, can strengthen the memory trace. e spacing effect has been found across tasks and amongst varying age groups, as spacing information improves retention, compared to massed presentation, speci�cally in the long term [12]. e most effective form of spacing has been debated, with evidence supporting bene�ts of both equal and expanded spacing, with no reliable differences between the two [13,14]. Equal spacing refers to intervals of equal length (e.g., every interval is one minute), while expanded spacing involves increasing time intervals (e.g., the �rst interval is 30 sec, the next 1 minute, the next 2 minutes, and so on). Interestingly, expanded retrieval has proven effective in both young [15] and older adults with memory impairment [16,17]. A more recent study by Hochhalter et al. [18], involving persons with dementia, found comparable bene�t for equal and expanded interval retrieval. It appears, regardless of the type of spacing, that there is a bene�t to spacing of information and recall for learners across the lifespan.
Not only is the spacing of information and retrieval important, but so too is the type of experience and feedback during performance. e feedback of interest in this paper is the acknowledgement of correct or incorrect performance, referred to as trial and error (or errorless) learning. Trial and error involves learning in which attempts are made, errors are experienced, and more revised attempts are experienced (e.g., if that did not work maybe this will). In contrast, errorless learning requires the participant to have limited experience with error. is is achieved by observation of the correct performance and practice of that performance. Although in many cases trial and error may provide unique information by which to learn, this error must be minimized in some sense to limit the possible solutions to a proposed action [19]. Errorless learning was selected for this experiment so that it could be replicated in the future with clinical populations for comparison of this motor communication task across the lifespan. Errorless learning is thought to be bene�cial for rehabilitation in persons with memory disorders as it reduces load on working memory [20]. Speci�cally, errorless learning has been found to enhance learning and memory, compared to errorful learning, in persons with amnesia [20].
e combined effect of enactment, expanded retrieval, and errorless learning for a motor communication task is not well understood. ere is also a lack of evidence to accurately characterize the modulation of these effects across the lifespan. Evidence for improved roll of enactment and spaced retrieval in older, cognitively-impaired persons suggests that motor bene�ts may increase with greater cognitive challenge. is has implications for cognitive challenge and natural memory loss with aging.
e following studies were designed to leverage the bene�ts of environmental enrichment and active recall to improve memory. In the present study we examined the enactment effect, compared to recognition learning, using an expanded retrieval, errorless protocol in young (Experiment 1) and older persons (Experiment 2).

Experiment 1
e task selected for this experiment was learning of hand shapes for letters and words in American Sign Language (ASL). Sign language is a motor communication task that, for the learner, pairs the English word with the sign language hand-shape. is task was selected because it provided an opportunity for new learning (forming hand shapes) while contextually familiar (use of English letters, words) and involved physical engagement. Expanded retrieval was used for recall of signs to test this schedule's intrinsic ability to improve memory, and examine the combination of enactment and expanded retrieval. An errorless learning protocol was selected to examine the characteristics of learning this motor task in absence of error experience. We hypothesized that enactment would improve learning, memory and retention of learned items, and result in better overall performance in comparison to merely learning to recognize items.

Participants.
Twenty participants, aged 18-30 (eight males and 12 females), were recruited from McMaster University's graduate and undergraduate population. All participants provided informed consent, approved by the McMaster University Human Research Ethics Board. Exclusion criteria involved any prior experience with sign language, collected via self-report.

Method.
Participants were assigned to one of two groups: enactment or recognition. Each group viewed an expert performing a sequence of hand shapes and were asked to review this video with the aim of (a) recognizing the sign in a future viewing (recognition group) or (b) enacting the sign in a future cued scenario (enactment group). Hand shapes represented letters and words in ASL, and were presented in groups of 3-6. Hand shapes increased in difficulty and number per set as the experiment advanced in order to maintain an increasing level of challenge for participants.
e recognition group was encouraged to watch the video multiple times to gain familiarity with the signs. e name of each sign was written in English at the top of the video. Participants were instructed not to attempt to form the signs with their hands. During recall, aer the initial viewing, participants in this group viewed the same video of expert performance without the names of each sign written on the slide.
e enactment group was encouraged to create hand shapes along with the expert viewed on the video at the beginning of each set. e video showed a close up view of the expert, torso and face, completing hand-shapes in ASL. Aer each recall interval participants were presented with the letters or words in English and asked to form the ASL hand shape for those items. All trials were �lmed to ensure proper formation of hand shapes. Time intervals between recall were expanding, 10 s, 20 s⋯160 s (see Figure 1). During intervals participants were engaged in one of three computer games: blackjack, hi-lo, or a shell game. e interference in the computer game was nonmotor; participants instructed the experimenter on which moves, selections they wanted to make.
If the participant had successfully recalled items from the �rst to the last time point (from 30 seconds, all the way to 160 seconds), they moved on to the next set of signs. If an error was made they returned to the instructional slide and began the interval sequence again. Once the second set of signs was completed participants were asked to recall the signs from the previous set. If they were unable to recall the signs in the previous set the experiment ended. e experiment was halted at this point on the assumption that if the participant was unable to remember the previous set of signs, that they had reached their short-term memory capacity, and could retain no new information without replacing the older information.
Participants were asked to perform an immediate recall test of all signs they had practiced (in the same order) and a random recall test (items were presented in a random order), if participants failed to recall a sign in sequence the test was discontinued. Participants returned six to eight weeks later for a retention test, in which they were asked to recognize signs from the expert video, as well as enact signs when prompted with the English word. All participants performed both retention tests; therefore each group had one familiar recall and one unfamiliar (based on their original learning condition).
Dependent Measures. Number of items recalled was compared within group across retention sessions as well as between groups. ere were three data points, immediate recall, random recall, and retention. Immediate recall was the number of items recalled by participants during the learning session. Random recall was the recall for items in a order different from that of learning. e �nal retention test occurred six weeks aer the initial learning session. Participants were required to recall items by recognizing them in the expert video, or performing hand-shapes when prompted by the English word. A total of thirty-two letters and words were presented to participants in this experiment. At the �nal retention test participants were asked to recall half the items via recognition of expert performance, and the other half through enactment of signs when an English word was presented. is created a familiar recall (recall in the method engaged during learning) and an unfamiliar recall (recall in a different method then engaged during learning).
Rate of forgetting was calculated by subtracting retention from immediate recall, dividing by immediate recall and multiplying by 100 to calculate a percentage. Rate of forgetting represented the proportion of signs learned that were recalled at the retention period. is measure allows for comparison between participants and groups with variable number of items recalled. Rate of forgetting represents the strength of memory for items.

Results.
A 2-factor between/within ANOVA was used to analyze number of items recalled between and within groups. e values used in the ANOVA were immediate recall and �nal retention test (aer 6 weeks) for the recognition and enactment groups. ere were no signi�cant differences between the recognition and enactment groups. Comparison of condition, in immediate recall and retention, revealed a signi�cant difference ( (1, 36) = 254.18, < 0.01) with the retention test eliciting a signi�cantly lower number of items remembered than the recall test (i.e., there were a signi�cant number of items participants "forgot" during the retention period). Rate of forgetting was compared between groups using a t-test to determine if enactment had a greater or lesser rate of forgetting compared to recognition; differences reached signi�cance ( (18) = 1.848, < 0.05, 1-tailed). e recognition group had a signi�cantly greater rate of forgetting then the enactment group (see Figure 2- Table 1 for group means and standard deviations). ere was no signi�cant difference in items recalled in the familiar condition between the enactment ( = 5.8) and recognition groups ( = 5.18), ( (18) = 0.56, = 0.577). is �nding suggests that encoding through enactment or recognition provided equivalent bene�t at recall when the items were recalled in a familiar method (enactment of signs for the enactment group, and recognition of signs for the recognition group).
ere was a signi�cant difference in items recalled in the unfamiliar condition between enactment ( = 6.55) and recognition groups ( = 2.91), ( = 2.65, = 0.0164). is �nding suggests that encoding through enactment provided a greater bene�t at recall for items in an unfamiliar context, compared to recognition. e enactment group was better at recognizing signs performed by an expert, compared to the recognition group's ability to enact signs at recall. ceiling effect has been found previously in younger adults in enactment encoding conditions [21], but this has not been in direct comparison to recognition. is lack of difference may be a result of insufficient challenge at the initial learning stage, or redundancy of sensory information from visual observation and physical engagement. e signi�cant difference in rate of forgetting suggests that bene�ts of enactment may exist in the strength of the memory for items learned. Participants in the enactment group recalled a greater proportion of signs at the 6-week retention test, demonstrating a better memory for items than those in the recognition group. e lack of enactment effect in number of items recalled in the younger group may be a result of several factors: a ceiling effect, errorless protocol at recall, or nature of the task. ere was a ceiling effect during learning, with most participants recalling all items during the acquisition period (a total of 32). Another possible explanation may be the errorless format of the recall sessions. e random recall session was ended immediately if a participant was unable to recall a sign, but this limited our ability to capture any signs later in the order of recall. Both groups experienced a signi�cant decrease in number of items recalled at retention, demonstrating signi�cant rates of forgetting. is decrease could be a result of poor encoding at learning and initial recall, or due to the length of the retention period, six weeks. e nature of the task, motor communication, may have been very intuitive to participants, and not provided the level of challenge required to engage the enactment effect. Comparison of familiar versus unfamiliar retention scores revealed that the enactment group demonstrated signi�cantly better retention scores in the unfamiliar retention test. is �nding is in contradiction to theories such as encoding speci�city [22], and suggests an improved strength of memory with enactment encoding.

Discussion
Limitations. An errorless protocol was extended into the random recall portion of the experiment. Immediate recall was used for comparison because this may have arti�cially reduced the number of items recalled by a participant. If a participant had difficulty remembering a particular sign they were prevented from recalling any other signs that occurred later in the recall order. As a result, the errorless protocol was not applied in experiment two. e length of the retention period may have contributed to lack of effect, and therefore, was adjusted to capture a more accurate picture of recall in the older cohort.

Experiment 2
In Experiment 2 the hypothesis remained the same, that enactment would improve learning, memory and retention of learned items, and garner better overall performance in comparison to merely learning to recognize items. If errorless learning can be bene�cial when explicit learning, or working memory, is challenged [20,23], then enactment paired with errorless learning should improve performance in older adults compared to a recognition protocol.

Participants.
All participants were recruited using advertisements in an online news outlet (the McMaster University Daily News) and posters on campus. All participants provided informed consent. Fieen participants aged 54-77, ten females and �ve males, were tested. Groups were pseudobalanced with the goal of equating for gender and age. Exclusion criteria involved any prior experience with sign language, collected via self-report.

Method.
All participants were briefed about the format of the experiment prior to beginning. e experimenter administered the mini-mental state exam to each participant, and the data were used for within-cohort comparison only. Participants were assigned to one of two groups: recognition or enactment. e protocol of this experiment was identical to that of experiment one, up to the point of the random recall component. For this experiment, during the random recall test, participants were able to "skip" a sign they could not recall and continue the test.
e spacing and number of retention tests were also adjusted for this experiment. Participants returned one week and two weeks aer the initial session for retention testing. At the �nal retention test participants were asked to recall half the items via recognition of expert performance, and the other half through enactment of signs when the English word was presented. is created a familiar recall (recall in the method engaged during learning) and an unfamiliar recall (recall in a different method then engaged during learning).
Two measures were used to ensure homogeneity of groups in the older cohort: a mini-mental state exam (MMSE) and a tactile discrimination task. e MMSE was included to ensure that participants did not suffer from any signi�cant memory impairment prior to participation. e purpose of the tactile discrimination task was to capture the motor ability to discriminate between nonsense shapes and familiar letter shapes. is was included to parse out the ability to link motor information to meaning, letters or language, or to nonsense shapes, or physical information lacking a speci�c context. e participants were asked to complete a letter and nonsense shape tactile discrimination task [24]. Participants were blindfolded and asked to "feel" a shape with the right hand. e blindfold was removed and the participant was asked to select the shape they had felt from a screen containing 6 letters and/or shapes. e test was repeated with the le hand. ere were a total of 8 shapes and letters.
A 2-factor ANOVA was used to analyze within and between group differences. ere were no signi�cant differences between the recognition and enactment groups ( (1, 26) = 0.265, > 0.05). ere was a main effect of condition, immediate recall and retention, ( (1, 26) = 4.611, < 0.05). Rate of forgetting was 23% and 51% for the enactment and recognition groups, respectively. e difference between rates of forgetting was signi�cant ( (13) = 2.128, < 0.05), with the recognition group having a higher rate of forgetting when compared to the enactment group (see Table 1 for group means and standard deviations). ere was no signi�cant difference in items recalled in the familiar condition between the enactment ( . is �nding suggests that encoding through enactment or recognition provided e�uivalent bene�t at recall when the items were recalled in a familiar method (enactment of signs for the enactment group, and recognition of signs for the recognition group).
3.4. Discussion. MMSE data revealed no signi�cant differences in cognitive ability between groups for the older adults. Analysis of tactile discrimination task results revealed that all participants had the capacity to learn to discriminate between language associated and non-sense shapes. ere was a sig-ni�cant difference in the number of correct discriminations in the right hand between groups, with the enactment group having a greater number of correct discriminations in the right hand compared to the recognition group. is may be explained by differences in handedness.
Although there was a trend towards enactment improving performance at retention in the older group, the betweengroup difference failed to reach signi�cance for overall number of items recalled. Differences in condition illustrate the signi�cant number of items forgotten between recall sessions. Rate of forgetting was signi�cantly different between groups, with the recognition group having a greater rate of forgetting, remembering a lower proportion of signs at retention compared to the enactment group. Individuals in the recognition group recalled more items during training and at immediate recall, but had a greater rate of forgetting. Individuals in the enactment group did not learn or recall as many items at training and immediate recall but retained a greater proportion of what they did learn at retention. is �nding suggests that the bene�t of enactment is not in volume of items learned but the strength of memory for those items. e strength of memory, in the case of older adults, improved overall number of items recalled but did not signi�cantly impact performance in familiar or unfamiliar recall.

Comparing Experiment 1 and 2 Results
In order to understand how the effect of enactment may be modulated by age a comparison was completed between experiment one and two. e difference between protocols experienced by the younger and older cohorts included the difference in retention period (6-8 weeks for the younger adults, and 3 weeks for the older adults), and the use of errorless learning at randomized recall (used for the �rst half of younger adults but removed for the second half of younger adults, and the older adults). e randomized recall score was not used for comparison within or between groups or cohorts. If the reduction in retention period in�uenced this comparison, we would assume that overall number of items recalled would be higher for the older adults (with shorter retention period) than young adults, but this was not found. e �nding suggests that comparison between the two experiments is appropriate, even given the differences in retention period.
A three-factor ANOVA was used to compare the results of the �rst and second experiments. ere was a signi�cant effect of age for number of items recalled ( (1, 62) = 57.02, < 0.05), condition ( (1, 62) = 94.29, < 0.05), and a signi�cant interaction between age and condition ( (1, 62) = 30.79, < 0.05). Holm-Sidak post hoc analysis of this interaction, revealed a signi�cant difference for age within enactment, with older adults performing better relative to young ( (1) = 6.519, < 0.05), and age within recognition, with younger performing better then older adults ( (1) = 7.198, < 0.05) (see Figure 2). A post hoc power calculation was done to help determine the accuracy of statistical outcomes for the comparison of enactment and recognition groups for younger ( = 0.9) and older adults ( = 0.64). e Cohen's value for both the young and older adults suggests that the statistical result carries practical signi�cance (i.e., decreased risk of type II error was made, [25]).

General Discussion
ese results support a bene�cial role for enactment in learning and recall [11]. is bene�cial role may be due to the engagement by the subject in performance of task, as well as the observation of the experimenter completing the task, both of which have been found to produce an enactment effect [26]. ere are several limitations to analysis between these two experiments, namely the ceiling effect of performance in young at initial learning and the alterations in the retention protocol for the older adults. Keeping in mind these challenges we compared the two groups in an attempt to characterize the differences in the way each age group utilized motor information in the form of enactment. Both young and older adults experienced a reduced rate of forgetting with enactment, improving strength of memory for items compared to the recognition group. ere were signi�cant differences in initial learning, clearly identifying a capacity difference in young versus older adults. e apparent increased bene�t from enactment for number of items recalled with age may be related to cognitive ability or differences in memory capacity that can be challenged with age. It has been suggested that multisensory input can be highly redundant [27]. erefore, when all systems are supposedly operating at their best, such as in young cognitively healthy adults, there is no added bene�t from motor information. For the older learners, all systems may be challenged, with cognitive or short-term memory impairment; this may be offset by integration of motor information to strengthen memory. is interaction suggests that motor information may provide compensatory information to bolster memory systems challenged by age related declines in performance.

Conclusion
Results from these experiments show an apparent age effect of enactment, with young experiencing no added bene�t of enactment across learning or retention, and older participants nearing a signi�cant improvement with enactment. is suggests a bene�t of the use of motor information encoding during enactment in the presence of cognitive or short-term memory challenge. Further research should focus on examining this effect in persons with memory impairment, speci�cally dementia. Utilizing this protocol with persons with dementia will add to the enactment literature in this population, and may reveal a valid therapeutic tool for communication later in the disease. Using a motor communication task may increase the quality and quantity of communication for persons with word �nding and verbal memory impairments, improving quality of life.