Poster #2 - An association in 9-month-old children between tasks probing declarative and procedural memory.

• In Event: 3-106 - Poster Session 11
  In Poster Session: PS 11 Section - Attention, Learning, Memory

Integrative Statement

In adults, it is well established that declarative and procedural memory are dissociated neurocognitive systems. As different underlying neurological systems mature at different ages it is of theoretical interest to examine the emergence of this dissociation in infancy. In preverbal infancy, evidence suggests that the deferred imitation (DI) task taps the declarative memory system (Jones & Herbert, 2006; Richmond & Nelson, 2007). In adults, the serial reaction time task (SRT, Nissen & Bullmer, 1987) has been clearly linked to the procedural memory system (Janacsek et al., under review). An infant-friendly version of the SRT task was developed in order to examine procedural memory in infants. It has been posited that the two memory systems follow different developmental trajectories in early infancy, with procedural memory functional from birth while declarative memory matures later, during the first year (Schacter & Moscovitch, 1984). The different developmental trajectories could entail a lack of association between these systems. However, a correlation between the tasks could suggest a developmental dependency between these systems.

Twenty-eight infants (15 female), mean age 9.3 months (SD = 0.26), visited the lab twice, with about a week between the visits. Another 10 infants were tested but did not complete all DI tasks (n = 1) or the SRT task (n = 9). Over the two visits, infants were presented with a total of eight established DI tasks, with their memory for the target actions being assessed after a 15 min delay. Performance of the target actions was coded from video. Their score was calculated as the sum of the performed target actions (mean = 4.6, SD = 2.35), with a possible maximum of 12. At the second visit, infants were also tested with the newly developed infant SRT. In this task, infants learn a visuo-spatial sequence by viewing three blocks of 5-item sequences followed by a block of randomly ordered items. The stimuli consisted of novel child-friendly pictures. Eye movement data, which was collected on a Tobii T120 eye tracker, was assessed for the latencies of saccades towards appearing stimuli. Sequence learning was operationalized as smaller mean saccade latency for the final sequence block than for the random block. Sequence learning was confirmed by the children’s performance, t(27) = 2.14, p = .042, two-tailed.

In order to test the relation between the DI and SRT tasks, we computed the correlation between the total DI score and the SRT learning score. The results indicated a significant correlation, spearman r(27) = .41, p = .033. This suggests that solving tasks that are thought to tap declarative and procedural memory respectively at 9 month of age, show a strong overlap in performance. This may be explained by a relation between these emergent memory systems and/or underlying resources that are needed to complete these tasks.
These results may have implications for the understanding of early memory development, in particular the developmental trajectories of procedural and declarative memory.

Authors

• Felix-Sebastian Koch, Linköping University
  Presenting Author

• Anett Sundqvist, Linköping University
  Non-Presenting Author

• Ulrika Birberg-Thornberg, Linköping University
  Non-Presenting Author

• Sandra Nyberg, Linköping University
  Non-Presenting Author

• Rachel Barr, Georgetown University
  Non-Presenting Author

• Michael T. Ullman,, Georgetown University, Washington DC
  Non-Presenting Author

• Mary Rudner, Linköping University
  Non-Presenting Author

• Mikael Heimann, Linköping University
  Non-Presenting Author