Eye movements in Sally-Anne false-belief tasks appear to reflect the ability to implicitly monitor the mental states of other individuals (theory of mind, or ToM). It has recently been proposed that an early-developing, efficient, and automatically operating ToM system subserves this ability. Surprisingly absent from the literature, however, is an empirical test of the influence of domain-general executive processing resources on this implicit ToM system. In the study reported here, a dual-task method was employed to investigate the impact of executive load on eye movements in an implicit Sally-Anne false-belief task. Under no-load conditions, adult participants displayed eye movement behavior consistent with implicit belief processing, whereas evidence for belief processing was absent for participants under cognitive load. These findings indicate that the cognitive system responsible for implicitly tracking beliefs draws at least minimally on executive processing resources. Thus, even the most low-level processing of beliefs appears to reflect a capacity-limited operation.And here, slightly edited, is some essential background material from their introduction:
A key paradigm for assessing ToM abilities is the Sally-Anne false-belief task: In still images, movies, or “live” performance (with puppets, actors, or both), “Sally” sees an object (e.g., a ball) being placed in a container. Sally then leaves the room. Next, “Anne” hides the object in a different container. When Sally returns to the room, participants are required to identify the location where they think Sally will first look for the object. To succeed at the task, participants must select (e.g., point to) the location that is consistent with Sally’s belief, as opposed to the actual, known location of the object.
Passing this explicit Sally-Anne task is thought to reflect a developmental milestone, which is typically achieved by the age of 4 years. Such findings suggest that children understand other people’s beliefs by this age. However, recent research using a variety of implicit ToM tasks suggests that children as young as 7 months may be able to register other individuals’ beliefs. For example, monitoring of eye movement behavior in free-viewing false-belief scenarios has demonstrated that 2-year-olds preferentially look toward the location at which the actor believes the ball to be.
Do humans fail to understand other individuals’ internal mental states until the age of 4, or is this fundamental ability already present during the 1st year of life? To accommodate these seemingly incongruent findings, Apperly and Butterfill proposed that throughout the life span, ToM is subserved by two distinct systems. According to this framework, an earlier-developing system, which operates implicitly and is independent of the development of language and executive function (e.g., working memory), is responsible for efficient monitoring of belief-like states. A later-developing system, which is dependent on domain-general cognitive functions (e.g., executive function), allows conscious (explicit) ToM inferences. Evidence supporting this framework includes a dissociation found in adults with Asperger’s syndrome, who can pass explicit false-belief tasks but do not display eye movement patterns consistent with implicit ToM in a Sally-Anne free-viewing paradigm.