2018 Sat Poster 6754

Saturday, November 3, 2018 | Poster Session II, Metcalf Small | 3:15pm

False belief understanding requires language experience, but its precursor abilities do not
D. Gagne, S. Goico, J. Pyers, M. Coppola

Understanding that others have thoughts or beliefs different from one’s own, a “Theory of Mind” (ToM), is a fundamental aspect of interpersonal interactions (Watson et al., 1999), and is shaped by both biological and environmental factors. One environmental factor contributing to ToM development is exposure to language (Milligan et al., 2007; Peterson & Wellman, 2009).

Adult homesigners with 25+ years of life experience but little to no language exposure succeed on visual perspective taking and representational change tasks, but show limited understanding of false belief (Gagne & Coppola, 2017), indicating that false belief understanding may depend on language ability. However, because homesigners were tested as adults, the role of reduced language experience in visual perspective taking and representational change early in development remains unclear.

Here, we investigated the cognitive development of 35 deaf children and youth aged 6-22 years (M=13.9) who had 0-16 years of language experience (M=8.2) and who live in a large, but geographically isolated city in Peru. Each participant completed two visual perspective taking tasks (Level 1 and Level 2, Masangkay et al.1974), a representational change task (false photograph; Zaitchick, 1990), and an experiential task that assessed two types of false beliefs (appearance-reality and unexpected contents; Pyers, 2005). We hypothesized that variability in language experience and in age would predict performance on measures of false-belief, but not visual perspective taking and representational change.

Thirty-four of 35 participants passed the false photograph task, regardless of age or language experience (one participant was excluded from this analysis due to failure to understand the task). Language was not significantly related to either visual perspective taking task (Figures 1-2) (PTL1: pearson’s r=0.1381, n=29, p=0.477, two-tailed; PTL2: pearson’s r=0.0953, n=25, p=0.649, two-tailed). Seven participants succeeded on the appearance-reality measure and eleven succeed on the unexpected contents measure. Performance on each measure of false belief was affected by language differently. Appearance-reality (AR) success was predicted by the interaction of maturational age and amount of time since first exposure to language (Figures 3-4) (ß=-0.155, p=0.021); participants who were older and had more language experience were more likely to succeed on appearance-reality. Our measures of language exposure, however, did not predict performance on the unexpected contents (UC) measure (ß=-1.532, p=0.126).

Performance on representational change tasks and visual perspective taking tasks remain unaffected by language regardless of age, confirming previously reported findings of typical visual perspective taking and representational change abilities among language delayed deaf children (Shield et al., 2016). In this population of deaf Peruvians, we observed highly variable false-belief performance that is not straightforwardly linked to participants’ self-reported measure of language experience. In sum, delayed language experience into adulthood selectively impairs false-belief understanding, evidenced by the large numbers of participants who should have passed false belief based on their maturational age (n=28 for AR and n= 24 for UC), but who nevertheless succeeded on the earlier milestones associated with ToM.