Visual statistical learning in infancy: Discrimination of fine-grained regularities depends on early test trials.

Infants' ability to detect statistical regularities between visual objects has been demonstrated in previous studies (e.g., Kirkham et al., Cognition, 83, 2002, B35). The extent to which infants extract and learn the actual values of the transitional probabilities (TPs) between these objects nevertheless remains an open question. In three experiments providing identical learning conditions but contrasting different types of sequences at test, we examined 8-month-old infants' ability to discriminate between familiar sequences involving high or low values of TPs, and new sequences that involved null TPs. Results showed that infants discriminate between these three types of sequences, supporting the existence of a statistical learning mechanism by which infants extract fine-grained statistical information from a stream of visual stimuli. Interestingly, the expression of this statistical knowledge varied between experiments and specifically depended on the nature of the first two test trials. We argue that the predictability of this early test arrangement-namely whether the first two test items were either predictable or unexpected based on the habituation phase-determined infants' looking behaviors.

Shared or separated representations for letters with diacritics?

Understanding the front end of visual word recognition requires us to identify the processes by which letters are identified. Since most of the work on letter recognition has been conducted in English, letter perception modeling has been limited to the 26 letters of the Latin alphabet. However, many writing systems include letters with diacritic marks. In the present study, we examined whether diacritic letters are a mere variant of their base letter, and thus share the same abstract representation, or whether they function as separate elements from any other letters, and thus have separate representations. In Experiments 1A and 1B, participants performed an alphabetical decision task combined with masked priming. Target letters were preceded by the same letter (e.g., a-A), by a diacritic letter (e.g., â-A), or by an unrelated letter (e.g., z-A). The results showed that the primes sharing nominal identity (e.g., a) facilitated target processing as compared to unrelated primes (e.g., z), but that primes that included a diacritic mark (e.g., â) did not, with reaction times being similar to those in the unrelated priming condition. In Experiment 2 we replicated these results in a lexical decision task. Overall, this demonstrates that as long as diacritics are used in scripts to distinguish between lexical entries, the diacritic letters are not mere variants of their base letters but constitute unitary elements of the script in their own right, with diacritics contributing to the overall visual shape of a letter.

Visual statistical learning in children and young adults: how implicit?

Visual statistical learning (VSL) is the ability to extract the joint and conditional probabilities of shapes co-occurring during passive viewing of complex visual configurations. Evidence indicates that even infants are sensitive to these regularities (e.g., Kirkham et al., 2002). However, there is continuing debate as to whether VSL is accompanied by conscious awareness of the statistical regularities between sequence elements. Bertels et al. (2012) addressed this question in young adults. Here, we adapted their paradigm to investigate VSL and conscious awareness in children. Using the same version of the paradigm, we also tested young adults so as to directly compare results from both age groups. Fifth graders and undergraduates were exposed to a stream of visual shapes arranged in triplets. Learning of these sequences was then assessed using both direct and indirect measures. In order to assess the extent to which learning occurred explicitly, we also measured confidence through subjective measures in the direct task (i.e., binary confidence judgments). Results revealed that both children and young adults learned the statistical regularities between shapes. In both age groups, participants who performed above chance in the completion task had conscious access to their knowledge. Nevertheless, although adults performed above chance even when they claimed to guess, there was no evidence of implicit knowledge in children. These results suggest that the role of implicit and explicit influences in VSL may follow a developmental trajectory.