Objectives: This study aims to compare verbal and motor implicit sequence learning abilities in children with and without specific language impairment (SLI). Methods: Forty-eight children (24 control and 24 SLI) were administered the Serial Search Task (SST), which enables the simultaneous assessment of implicit spoken words and visuomotor sequences learning. Results: Results showed that control children implicitly learned both the spoken words as well as the motor sequences. In contrast, children with SLI showed deficits in both types of learning. Moreover, correlational analyses revealed that SST performance was linked with grammatical abilities in control children but with lexical abilities in children with SLI. Conclusions: Overall, this pattern of results supports the procedural deficit hypothesis and suggests that domain general implicit sequence learning is impaired in SLI. (JINS, 2016, 22, 1–10)

According to the procedural deficit hypothesis (PDH), abnormal development in the procedural memory system could account for the language deficits observed in specific language impairment (SLI). Recent studies have supported this hypothesis by using a serial reaction time (SRT) task, during which a slower learning rate is observed in children with SLI compared to controls. Recently, we obtained contrasting results, demonstrating that children with SLI were able to learn a sequence as quickly and as accurately as controls. These discrepancies could be related to differences in the statistical structure of the SRT sequence between these studies. The aim of this study was to further assess, in a group of 21 children with SLI, the PDH with second-order conditional sequences, which are more difficult to learn than those used in previous studies. Our results show that children with SLI had impaired procedural memory, as evidenced by both longer reaction times and no sign of sequence-specific learning in comparison with typically developing controls. These results are consistent with the PDH proposed by Ullman and Pierpont (2005) and suggest that procedural sequence-learning in SLI children depends on the complexity of the to-be-learned sequence. (JINS, 2013, 19, 1–8)

Recent studies on specific language impairment (SLI) have suggested that language deficits are directly associated with poor procedural learning abilities. Findings from our previous work are contrary to this hypothesis; we found that children with SLI were able to learn eight-element-long sequences as fast and as accurately as children with normal language (NL) on a serial reaction time (SRT) task. A probabilistic rather than a deterministic SRT paradigm was used in the current study to explore procedural learning in children with SLI to mimic real conditions of language learning. Fifteen children with or without SLI were compared on an SRT task including a probabilistic eight-element-long sequence. Results show that children with SLI were able to learn this sequence as fast and as accurately as children with NL, and that similar sequence-specific learning was observed in both groups. These results are novel and suggest that children with SLI do not display global procedural system deficits. (JINS, 2011, 17, 336–343)

Recent studies have reported abnormal implicit learning of sequential patterns in patients with schizophrenia. Because these studies were based on visuospatial cues, the question remained whether patients were impaired simply due to the demands of spatial processing. This study examined implicit sequence learning in 24 patients with schizophrenia and 24 healthy controls using a non-spatial variation of the serial reaction time test (SRT) in which pattern stimuli alternated with random stimuli on every other trial. Both groups showed learning by responding faster and more accurately to pattern trials than to random trials. Patients, however, showed a smaller magnitude of sequence learning. Both groups were unable to demonstrate explicit knowledge of the nature of the pattern, confirming that learning occurred without awareness. Clinical variables were not correlated with the patients' learning deficits. Patients with schizophrenia have a decreased ability to develop sensitivity to regularly occurring sequences of events within their environment. This type of deficit may affect an array of cognitive and motor functions that rely on the perception of event regularity. (JINS, 2005, 11, 659–667.)