The Effect of Probabilistic Context on Implicit Temporal Expectations in Down Syndrome

Abstract

One of the most important sources of predictability that human beings can exploit to create an internal representation of the external environment is the ability to implicitly build up subjective statistics of events' temporal structure and, consequently, use this knowledge to prepare for future actions. Stimulus expectancy can be subjectively shaped by hierarchically nested sources of prediction, capitalizing on either local or global probabilistic rules. In order to better understand the nature of local-global proactive motor control in Down Syndrome, in the present study a group of participants with Down Syndrome (DS group; n = 28; mean age 29.5 ± 13 years; range 10-54) and a group of typically developing participants matched by either gender or mental age (TD-MA group; n = 28; 5.6 ± 1 years; range 4-8) were administered a novel motor preparation task, defined as the Dynamic Temporal Prediction (DTP) task. In the DTP, the temporal preparation to imperative stimuli is implicitly shaped by the local increase of expectancy. This is manipulated trial-by-trial as a function of the preparatory foreperiod interval (Stimulus-Onset Asynchrony or SOA). In addition, temporal preparation can be also implicitly adjusted as a function of global predictive context, so that a block-wise SOA-distribution bias toward a given preparatory interval might determine a high-order source of expectancy, with functional consequences on proactive motor control adjustment. Results showed that in both groups motor preparation was biased by temporal expectancy when this was locally manipulated within-trials. By contrast, only the TD-MA group was sensitive to global rule changes: only in this cohort was behavioral performance overall impacted by the SOA probabilistic distribution manipulated between-blocks. The evidence of a local-global dissociation in DS suggests that the use of flexible cognitive mechanisms to implicitly extract highorder probabilistic rules in order to build-up an internal model of the temporal properties of events is disrupted in this developmental disorder. Moreover, since the content of the information to be processed in the DTP task was neither verbal nor spatial, we suggest that atypical global processing in Down Syndrome is a domain-general rather than specific aspect characterizing the cognitive profile of this population.

Grounding Adaptive Cognitive Control in the Intrinsic, Functional Brain Organization: An HD-EEG Resting State Investigation

“…All participants performed a warned simple reaction time (RT) task adapted from an experimental paradigm previously employed from our lab to investigate voluntary and automatic temporal attention effects in adults and school-aged children [21]. This task, defined as Dynamic Temporal Prediction (DTP) [14,22] was originally conceived to investigate children's behavioral performance in relation to either local or global probabilistic rules as two distinct sources of temporal predictability. We used a modified version adapted for ERP investigation here.…”

Implicit learning of non-verbal regularities by deaf children with cochlear implants: An investigation with a dynamic temporal prediction task

“…According to previous literature [33,35,37,41,42], we expected all children to be able to use the local predictive rule to shape their behavioural performance. Due to the classic foreperiod effect, we expect faster reaction times for long as compared to medium or short foreperiod intervals, regardless of the global properties of the task.…”

“…A secondary aim of this study is to propose the DTP as an assessment tool for implicit learning that can avoid confounding explicit factors. Indeed, this task is designed to limit the interference of the explicit processes of working memory and has already been found reliable to elicit implicit learning of global temporal contingencies in children with typical [32] and atypical development (i.e., Down Syndrome; [37]). To avoid verbal recoding and rehearsal, the task requires participants to proactively adjust motor control on the basis of temporal regularities instead of sequences.…”

Adaptive Cognitive Control in Prematurely Born Children: An HD-EEG Investigation

“…Albeit limited, the extant evidence on typical development suggested the possibility of assessing ACC as a marker of potential clinical relevance for atypical development, which has been scarcely investigated. In two studies using the DTP task we were able to show that the ability to implement ACC on the basis of global predictability is disrupted in Down syndrome [ 42 ] and focal epilepsy of childhood [ 43 ]. Conversely, deaf children with cochlear implants (a condition of neurodevelopmental risk for academic outcomes; [ 44 ]) showed comparable ACC performance as typically hearing children, suggesting that implicit learning might be resilient to early adverse experiences such as a lack of auditory stimulation [ 45 ].…”

“…Noteworthy, unlike traditional cognitive control tasks (i.e., Stroop, flanker or Simon) the DTP task does not include a conflict condition, ruling out any potential confound deriving from excessive working memory load or complex instructions, as the only instruction is to press a button when the target occurs. This makes it suitable for investigating ACC in young typically [ 41 ] and atypically [ 42 , 43 , 45 ] developing children, including PT children. Nonetheless, in the context of the DTP, task ACC is crucial for the efficient adaptation to both local and global patterns.…”