Patterns of Interference in Sequence Learning and Prism Adaptation Inconsistent With the Consolidation Hypothesis

Abstract

The studies reported here used an interference paradigm to determine whether a long-term consolidation process (i.e., one lasting from several hours to days) occurs in the learning of two implicit motor skills, learning of a movement sequence and learning of a visuo-motor mapping. Subjects learned one skill and were tested on that skill 48 h later. Between the learning session and test session, some subjects trained on a second skill. The amount of time between the learning of the two skills varied for different subjects. In both the learning of a movement sequence and the learning of a visuo-motor mapping, we found that remote memories were susceptible to interference, but the passage of time did not afford protection from interference. These results are inconsistent with the long-term consolidation of these motor skills. A possible difference between these tasks and those that do show long-term consolidation is that the present tasks are not dynamic motor skills.The notion that memories initially exist in a labile state and with time become stable was first proposed in 1900 by Müller and Pilzecker (cited in Lechner et al. 1999). These researchers found that memory for a list of words was disrupted if new information was learned less than 1 min later, but not if learned 10 min later. They concluded that the memories had undergone a stabilization process, which they termed consolidation. In the current study, we will use the term consolidation to refer to the stabilization of memory (i.e., a decrease in susceptibility to forgetting via decay or interference) in the absence of further practice of that memory. There are two putative phases of consolidation processes, short-term consolidation processes, which operate over a period of seconds to hours post-training and are mediated by local cellular mechanisms resulting in longterm potentiation (LTP), and long-term consolidation processes, which operate over a period of hours to months post-training and are mediated by neural reorganization (for review, see McGaugh 2000;Dudai 2002). The focus of the current study is on long-term consolidation processes. Much of the research on long-term consolidation processes has focused on explicit memory tasks, tasks in which memory is demonstrated through conscious recollection of previously learned information (Schacter 1987). Although less consolidation research has focused on implicit memory tasks, tasks in which memory is revealed through performance and does not require conscious recollection of learned information, recent interest in the long-term consolidation of motor learning is one exception (BrashersKrug et al. 1996). The experiments described here were designed to assess whether a long-term consolidation process is ubiquitous for different components of motor skill learning.Although there is much evidence that a long-term process of consolidation is evident in performance on explicit memory tasks (e.g., Squire et al. 1989;Zola-Morgan and Squire 1990), it is not immediately apparent that a long-term consolidation proc...

Time-Limited Consolidation and Task Interference: No Direct Link

“…It is not a universal finding (Aberg and Herzog, 2010), and in studies that did report interference, it was found for widely varying time intervals, from 0 h up to 4 h in some studies (Brashers-Krug et al, 1996;Shadmehr and Holcomb, 1997;Seitz et al, 2005), to 24 h up to a week in others (Goedert and Willingham, 2002;Caithness et al, 2004;Zhang et al, 2008). These findings raise fundamental questions about the notion of time-limited consolidation and its relation to behavioral interference.…”

Spatial habit competes with effort to determine human spatial organization

“…Consistent with this notion, individuals in the present investigation maintained the initial configurations of objects despite it being more effortful for task execution. In addition, the strength of association between a given context and action can also influence habit formation (e.g., Goedert & Willingham, 2013) and, in Experiments 1a and 1b, the more individuals had used a given configuration prior to the the final block. Lastly, past experiments have shown that a formally learned context-action coupling can inhibit the formation of subsequent ones (Wood & Neal, 2007).…”

Offline consolidation in implicit sequence learning

“…During this interval, there is no further practice, or even mention, of the procedure, and learning remains largely tacit or implicit (Brown & Robertson, 2007;Hallgato, Gyori-Dani, Pekar, Janacsek, & Nemeth, 2013;Krakauer & Shadmehr, 2006;Németh et al, 2010). Consolidation is also sometimes referred to as resistance to interference and forgetting (Ghilardi, Moisello, Silvestri, Ghez, & Krakauer, 2009;Goedert & Willingham, 2002;Stephan, Meier, Orosz, Cattapan-Ludewig, & KaelinLang, 2009). In the present study, we use the first definition (i.e., further improvement or enhancement).…”

“…We tested whether consolidation would OFFLINE CONSOLIDATION 7 differ for the learning of probabilistic and deterministic sequences, in particular, whether it might be stronger for deterministic sequences (see Deroost, Zeeuws, & Soetens, 2006;Destrebecqz & Cleeremans, 2001;Wilkinson & Jahanshahi, 2007). In fact, it has been shown that when sequence structure is complex, as it is for probabilistic sequences, offline consolidation of sequence learning may not occur (Goedert & Willingham, 2002), or at least not unless the sequence is explicit and not without an interval including sleep (see Cohen & Robertson, 2007;Song, 2009). …”