Brief article Eighteen-month-old infants show false belief understanding in an active helping paradigm David Buttelmann * , Malinda Carpenter, Michael Tomasello Department of Developmental and Comparative Psychology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany article info Article history: Received 2 May 2008 Revised 14 April 2009 Accepted 13 May 2009 Keywords: False belief Helping Theory of mind Infancy abstract Recently, several studies have claimed that soon after their first birthday infants under- stand others’ false beliefs. However, some have questioned these findings based on criti- cisms of the looking-time paradigms used. Here we report a new paradigm to test false belief understanding in infants using a more active behavioral response: helping. Specifi- cally, the task was for infants to help an adult achieve his goal – but to determine that goal infants had to take into account what the adult believed (i.e., whether or not he falsely believed there was a toy inside a box). Results showed that by 18 months of age infants successfully took into account the adult’s belief in the process of attempting to determine his goal. Results for 16-month-olds were in the same direction but less clear. These results represent by far the youngest age of false belief understanding in a task with an active behavioral measure. Ó 2009 Elsevier B.V. All rights reserved. 1. Introduction There is currently much controversy about the age at which young children first understand that others may hold false beliefs. Classically, it was thought that young children first understand false belief at around 4–5 years of age, when they pass verbal tests such as the change-of-location (Sally-Anne) and change-of-contents (Smarties) tests (see Wellman, Cross, & Watson, 2001, for a review). But, as is well known, these tests have fairly strong demands on chil- dren’s other cognitive skills (Bloom & German, 2000; Carl- son & Moses, 2001). When these demands are reduced, children pass false belief tests at closer to 3 years of age (e.g., Carpenter, Call, & Tomasello, 2002). Clements and Perner (1994) attempted to design a false belief test with an absolute minimum of extra cognitive demands. In this test, children saw a toy mouse leave its cheese at one location, then the cheese was moved when he was not looking, and children then heard the announce- ment that the mouse was coming back to get his cheese. The question was whether they would look to the place where the cheese really was, or rather to the old place where the mouse falsely believed it was. Children at 2;11, but not younger, seemed to anticipate that the mouse would act in accordance with his false belief. Recently, Southgate, Senju, and Csibra (2007) have used a similar anticipatory looking paradigm and found positive results with 25-month-olds. More controversially, several recent studies have claimed false belief understanding in 15- and even 13- month-old infants (Onishi & Baillargeon, 2005; Surian, Cal- di, & Sperber, 2007). The paradigm used in these cases is the violation-of-expectation paradigm. Infants looked longer at a scene in which a protagonist searched for an ob- ject in a place she could not know it to be (though it really was there) than to a scene in which the protagonist searched for an object where she had seen it hidden (but it no longer was). Some researchers have argued that in these tasks infants only need to notice that something is unusual; they do not need to attribute beliefs to the pro- tagonist (e.g., Perner & Ruffman, 2005; Sirois & Jackson, 2007; see also Haith, 1998). Both for these skeptics and for researchers willing to interpret these new findings in 0010-0277/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.cognition.2009.05.006 * Corresponding author. Tel.: +49 341 3550443; fax: +49 341 3550444. E-mail address: buttelmann@eva.mpg.de (D. Buttelmann). Cognition 112 (2009) 337–342 Contents lists available at ScienceDirect Cognition journal homepage: www.elsevier.com/locate/COGNIT