PERCEPTUAL-MOTOR SPECIFICITY 1 Running head: PERCEPTUAL-MOTOR SPECIFICITY On the specificity of perceptual-motor sequence learning

Motor skill expertise developed through practice is supported by implicit learning that leads to gradually improving performance. Previous studies examining this type of learning in the lab have used perceptual-motor sequence learning tasks, such as the Serial Interception Sequence Learning (SISL) task. In the SISL task participants respond to scrolling visual cues that follow a covertly-embedded repeating sequence, and gradually develop improved performance of a specific motor sequence through training. Previous work has demonstrated that altering any component of the motor sequence (e.g. timing) completely disrupts performance, suggesting that this knowledge is extremely inflexible. To test the hypothesis that this specificity extends to the perceptual stimulus component of the sequence, in the current experiment the perceptual information available to participants was selectively manipulated in a test condition that differed from training, while the motor response sequence was left intact. Participants were randomly assigned to train in either the Standard cue condition, with three to four cues on the screen at any time, or the Isolated cue condition, where increased cue velocity only allowed one cue on the screen at any given time. Compared to the sequence expression exhibited during the test that matched their training condition, participants in both conditions exhibited weak transfer to the untrained perceptual condition (~25-30%). This suggests that implicit skill learning leads to integration of information within and across modalities, suggesting that implicit learning will generally be specific to the training context and full transfer of knowledge to different contexts will be difficult to achieve. keywords: perceptual-motor learning, implicit, transfer, specificity PERCEPTUAL-MOTOR SPECIFICITY 3 On the specificity of perceptual-motor sequence learning Athletes train extensively to perfect the motor skills necessary to succeed at their chosen sport. When practicing, an athlete focuses on a particular skill in order to achieve the desired improvement. The directed practice that leads to motor skill expertise relies on two memory systems. The explicit memory system is responsible for instruction and top-down control; this is the system that typically comes to mind when one thinks of memory because it is how we store facts and events. Explicit knowledge is generally conscious and verbalizable, and is able to be used in a number of contexts (i.e. is flexible). The other memory system is implicit and supports performance improvements through repeated practice (Milner, Squire, & Kandel, 1998; Squire & Knowlton, 2000). This implicit system is generally nonconscious, and produces knowledge that is hard to verbalize. The lack of access to implicit knowledge also tends to be less flexible because there is no conscious access to the representation (Dienes & Berry, 1997). During skill learning, one uses explicit instructions to learn the rules or guidelines of a motor-skill, such as understanding the basics to hit a serve in tennis (throwing the ball in the air, timing your swing at the ball with the correct coordination, etcetera). Through continued practice, one gains implicit knowledge which leads to improved motor skill performance that eventually becomes automated. Those skills that once were not polished continually improve, and it is difficult to explain what exactly within this continued practice is causing the improvement. These improvements that underlie motor skill expertise are believed to rely on this inflexible, implicit learning. However, it is unclear if this practice will effectively help any other similar skills. For example, even though both a forehand and backhand tennis swing use similar techniques, it is difficult to know how much training your backhand will help your forehand. An PERCEPTUAL-MOTOR SPECIFICITY 4 athlete would hope to receive overall benefits from that practiced skill by being able to transfer that knowledge to similar contexts that contain some of the same components. Perceptual-motor sequence learning has served as an effective task for studying knowledge transfer in skill learning due to its relative simplicity while also allowing for separately manipulable perceptual and response elements. Participants’ learned sequence performance improvements that underlie motor skill expertise are believed to rely on implicit learning. Skill learning is theorized to be developed implicitly through several individual components being learned, such as motor-responses, timing, and perception. By manipulating task demands of perceptual-motor learning tasks, it has been possible to demonstrate learning of individual sequence components and reinforce the separability of component processes. Research has examined which components can be learned during practiced perceptual-motor sequence knowledge, but the transferability and expression of that knowledge is still in question. Models of transfer are based on the idea that transfer depends on the degree to which the component processes overlap between practice and performance. This is not a novel concept, and in fact is an idea that dates back over 100 years (Woodworth & Thorndike, 1901). Evidence concerning the underlying component processes in complex skill learning tasks can be found by examining transfer effects or failures to transfer from training to test conditions. Limitations in transfer following skill learning likely reflect the inflexibility of implicit knowledge that is best understood using a framework based on examining the overlapping knowledge components between the training context and a performance test. Sanchez, Gobel, & Reber (2010) demonstrated that the Serial Interception Sequence Learning (SISL) task is a reliable test of implicit perceptual-motor sequence learning. The SISL task is a videogame-like task where participants make timed keypress responses to verticallyPERCEPTUAL-MOTOR SPECIFICITY 5 scrolling cues on a computer screen. Unknown to the participants, the cues contain an embedded, intermittent, but repeating sequence to which their performance becomes improved compared to a random sequence of cues. Participants learned their repeated sequence over the course of the experiment and could not reliably indicate which sequence they had trained on. There was no explicit sequence knowledge developed, and participants were only able to express their sequence via performance. Gobel, Sanchez, & Reber (2011) previously found that changing either the order or timing of a learned motor performance in the SISL task eliminates previous practice effects. This result implied a fully integrated representation of action order and timing information that had not been observed in similarly structured studies using a slightly different paradigm (Shin & Ivry, 2002). If transfer is not always predicted simply by the overlapping components, it may also be necessary to account for the possibility of integration of information. If there is learning integration across components, transfer may require consistent information across multiple components. By changing one component of the sequence knowledge, both the transfer of that type of information along with any integrated representations on which it depends are significantly disrupted. This suggests that transfer will often be limited, and indicates that training gains may be restricted to contexts that contain very similar characteristics to training. Other previous perceptual-motor learning tasks have claimed that learned motor sequence knowledge is entirely represented in response locations (Willingham, Nissen, & Bullemer, 1989; Willingham et al., 2000), which would predict that transfer of knowledge across different conditions would be dependent on maintaining this single component. A perceptual-motor sequence study altered the stimulus presentation from a centrally-located digit during training to four spatially-mapped locations during a transfer test and found reliable sequence knowledge expression in the transfer condition (Willingham, 1999). While this result supports the learning PERCEPTUAL-MOTOR SPECIFICITY 6 of response location as a key component of sequence knowledge, the actual amount of transfer was not examined, which opens the possibility that knowledge expression was weaker after the perceptual change. Additional research has shown the importance of the perceptual-motor component in skill learning, while also examining the specificity of this knowledge. Robust learning of perceptual visual information has been reported (Fiser & Aslin, 2002) and sequence learning studies have found perceptual information to be a learnable sequence component (Deroost & Soetens, 2006). Beilock and Carr (2001) demonstrated that individual knowledge representations can be integral in the performance of learned skill knowledge. Slight changes to perceptual representations (in this case, the shape of a golf putter), while maintaining the exact same weight and motorresponse necessary significantly impaired performance. However, there are some additional benefits to using the SISL task as a mesaure of implicit skill learning compared to other perceptual-motor learning tasks. Multiple cues are visible on the screen at once which displays perceptual information across multiple sequence items that are specific to the trained sequence. This adds additional contextual information across sequence items and allows for motor planning of upcoming responses, making this information more useful for response completion and thereby potentially making it more likely to become a learned component when compared to other perceptual-motor learning tasks. This suggests that implicit learning processes operating on this more global perceptual information may be acquiring contextual effects of the overall stimuli presentation (Jiménez, Vaquero, & Lupiáñez, 2006), contributing to the set of component processes that m