Comprehension of the Referential Intent of Looking and Pointing Between 12 and 15 Months

Butler, Caron, & Brooks (2000) tested the gaze following of 14-and 18-month-olds under 3 conditions: (1) when the adult's view of the targets was blocked by barriers, (2) when the barriers contained open windows, and (3) no barriers. Contrary to a nonmentalist "ecological" model (adult turns serve as cues to the location of interesting events), frequency of gaze following by 14-month-olds was not equivalent across the 3 conditions. Contrary to a mentalist model (infant wants to see what the adult is seeing), gaze following was not substantially less in the barrier than in the window and no-barrier conditions (as was the case for 18-month-olds). To examine whether the barriers posed vector projection problems for essentially nonmentalist, or line-of-sight problems for essentially mentalist younger infants, 3 experiments were conducted. In Experiment 1, a 12-month group was tested in the same 3 conditions to determine if, being younger, they might yield a more clearcut nonmentalist pattern. Contrarily, they behaved like Butler et al.'s 14-month-olds. In Experiment 2, a 14-month group was tested in the barrier and window conditions, but now combining pointing with turning. Infants behaved as predicted by the mentalist model: strong responding in the window condition and minimal in the barrier (where many strained to look inside the partitions). In Experiment 3, an attempt was made to differentiate between mentalist and "geometric" (vector projection) interpretations of the results of Experiment 2 by testing another 14-month group with the adult's eyes closed while pointing. Gaze following now dropped precipitously in the window condition as did looking inside the solid barriers, indicating (1) that infants in Experiment 2 had not simply been guided to target by an extended arm, but construed it as part of a referential act that was as much visual as gestural, and (2) that by 14 months, infants may have acquired a mentalistic concept of seeing.