“Theory of mind” (ToM) is the ability to reason other people’s beliefs, intentions and desires (Baron-Cohen et al., 1985). Over the last two decades, there has been considerable developmental research into ToM using the “false-belief task” (e.g. Baron-Cohen et al., 1985, Wellman et al., 2001). The majority of research has established that ToM is present in young children and develops in a predictable sequence through childhood (Wellman & Liu, 2004). For example, by three years of age, children can understand that two individuals can hold different beliefs (Wimmer & Perner, 1983) and by age four, can understand that people can have “false-beliefs” contrary to reality (Wellman & Liu, 2004). Recent research has even demonstrated that adults have difficulties with false-belief tasks (Birch & Bloom, 2007).

However, a recent paper by Converse et al (2008) examined the role of incidental mood on ToM. Grounded in the view that ToM requires effortful and deliberative processing (Kahneman, 2003), researchers found that when distinguishing between one’s own and other’s beliefs, participants were facilitated by sad moods compared to happy moods. This is because happiness is associated with heuristic processing whilst sadness is associated with systematic and deliberative processing (Converse et al., 2008). In their study, adult participants underwent a musical mood induction procedure (MMIP) and were randomly allocated to two conditions (“happy” and “sad”). Those in the former condition were asked to listen to a song from a pre-selected list of happy songs whilst participants in the latter condition were required to listen to a sad song. Following the mood induction, participants completed a false-belief task in which they read one of two versions of a scenario and estimate a character’s behaviour. Whilst the character has the same knowledge in both versions, participants received different information. Researchers then measured low ToM use by observing whether participants had an increased reliance on their own private knowledge.

The study is an important contribution to the current body of knowledge on ToM as the findings suggest that a) mood states do have important consequences for mental-state inferences and b) variability in ToM studies may be explained by mood. However, despite these contributions, the study solely focused on a sample of adults and failed to explore how mood affects ToM use in children. This is an important oversight given that the majority of developments in ToM have been based on studies with children, therefore, suggesting significant implications for research if mood is found to significantly impact children’s ToM judgments. Moreover, given children’s increased susceptibility to mood induction (De Haan & Gunnar, 2009), mood may have even more potent effects on ToM in children.

This current study will therefore examine the role of mood in affecting ToM use in children for the first time. It will attempt to bolster previous findings that mood does influence ToM and clarify the role of mood in influencing deliberative processing in ToM. In so doing, the study will replicate the original procedure, but with modifications to the mood induction and the false-belief task. In fact, a clear strength of this study is that the false-belief task was originally devised to be used with children and not adults (Baron-Cohen et al., 1985), making the task particularly suitable for use with children. In addition, previous research has supported the fact that mood induction procedures can effectively impact children’s positive and negative emotions (Brenner, 2000).

Proposed Research

There are modifications made to the experimental procedure. As mood induction requires participants to follow explicit instructions, changes to the MMIP will be implemented according to the study’s sample of pre-school children. For example, although researchers (e.g. Dalla Bella et al., 2001) have found that most 5 year olds can distinguish positive and negative valence in music, a MMIP may not be sufficient for invoking moods in children. Children will therefore undergo an additional mood induction. Moreover, in the original study, adult participants completed a pre- and post- induction self-report (Positive-and-Negative Affect Schedule; Watson & Clark, 1994) to serve as a manipulation check. However, as a self-report is difficult to implement with young children, an alternative manipulation check is needed. There are also important ethical considerations associated with a MMIP in children. The experimenter will need to ensure that mood induction does not cause long-term effects, but is also not too short-lived to observe its effects.



100 children aged 4-6 years old will be recruited from local schools through flyers and e-mail bulletins.


On the day of testing, each child will be guided to an individual room. To provide a replication of the Converse et al (2008) study, a 2 X 2 between-subjects experimental design will include a mood induction and false-belief task. Researchers will randomly allocate children to 2 conditions: “happy” and “sad” and undergo the mood induction. Both groups then complete the same false-belief task. The entire procedure takes a total of 40 minutes.

Mood Induction.

The mood induction scenario for each condition will make amendments to the MMIP in the Converse et al (2008) study. Each child will first be shown a sheet of paper with a series of “smiley faces” ranging from very sad to very happy, and asked to point to the image that best describes how they feel. This is the baseline affect manipulation check. Children will then be instructed to listen to a song played via speakers. Children in the happy condition will listen to two songs from the original list of songs in the Converse et al (2008) study and children in the sad condition will listen to two sad songs. In both conditions, children will be explicitly told “Now, I am going to play a “happy” / “sad” song so please listen carefully to the song”. Children will then be presented with a model figure on a sheet of paper and asked to draw a replica of the figure on a plain sheet of A4 paper. In the happy condition, children will be presented with a smiling figure and in the sad condition, children will be asked to copy a sad figure. Following this, children will be presented with the sheet of faces and asked to point to the face which describes how they feel to provide a post-task rating of affect. A second manipulation check will be the size of their drawing as research has suggested that drawing size is associated with a child’s affect. Larger drawings indicative of positive affect and smaller drawings are indicative of negative affect (Forrest & Thomas, 1991).

False-Belief Task.

The false-belief task is the classic “Sally-Anne task” (Baron-Cohen et al., 1985). Each child is seated at a table with two dolls. The experimenter tells the child that the dolls are named Anne and Sally and checks that the child has understood these names. Each doll is placed in front of a basket and square box. The experimenter then enacts a scene in which a marble is hidden in Sally’s basket to ‘hide’ the marble with Anne looking on. Sally then “leaves the room” and the marble is then re-hidden in the box. Sally returns and the experimenter prompts the child with three questions:

‘Where will Sally look for her marble?’ (“belief question”) ‘Where is the marble really?’ (“reality question”) ‘Where was the marble in the beginning?’ (“memory question”) Predictions

There are a number of predictions for the current study. Firstly, it is expected that the findings of the original study will be replicated in the sample of pre-school children. That is, I expect that after controlling for age effects, children in the sad condition will score higher on the belief, reality and memory questions in the Sally-Anne task. This will be due to a greater deliberative processing associated with a sad mood. These findings will provide support for the idea that ToM requires deliberative processing and such processing is associated with sad moods rather than happy moods. Second, I expect that there will be a number of age differences in performance on the Sally-Anne task. I expect that younger children, due to their increased susceptibility to mood induction, will have a greatly diminished ToM on the Sally-Anne task due to the more pronounced impact of mood on their deliberative processing.

However, it must be noted that it is possible that the results of the current study will not replicate the original study. This may be due to a number of factors. Firstly, it is possible that the mood induction procedures are not powerful enough to invoke happy and sad moods for children or they produce effects that are too short term to observe any effects in the false belief task. Second, it may be that the deliberative processing associated with sad moods and the heuristic processing associated with happy moods is not developed sufficiently in pre-school children, and is only salient in adulthood. If this is the case, this provides impetus for future research focused on testing the influence of mood on ToM in older children and adolescents.


Baron-Cohen, S., Leslie, A. M., & Frith, U. (1985). Does the autistic child have a ‘‘theory of mind’’Cognition, 21, 37–46.

Birch, S. A. J., & Bloom, P. (2007). The curse of knowledge in reasoning about false beliefs. Psychological Science, 18(5), 382–386.

Brenner, E. (2000). Mood induction in children: Methodological implications. Review of General Psychology, 4, 264-283.

Converse, B. A., Shuhong, L., Boaz, K., & Epley, N. (2008). In the Mood To Get Over Yourself: Mood Affects Theory-of-Mind Use. Emotion, 8(5), 725-630.

Dalla Bella, S., Peretz, I., Rousseau, L., & Gosselin, N. (2001). A developmental study of the affective value of tempo and mode in music. Cognition, 80, B1-B10.

de Haan, M., & Gunnar, M.R. (2009). Handbook of Developmental Social Neuroscience. The Guilford Press.

Forrest, M. & Thomas, G.V. (1991). An exploratory study of drawings by bereaved

children, British Journal of Clinical Psychology, 30, 373-374.

Kahneman, D. (2003). A perspective on judgment and choice: Mapping bounded rationality. American Psychologist, 58, 697–720.

Watson, D., & Clark, L. A. (1994). The PANAS-X: Manual for the positive and negative affect schedule-Expanded Form. Iowa City: University of Iowa.

Wimmer, H.; Perner, J. (1983). “Beliefs about beliefs: Representation and constraining function of wrong beliefs in young children’s understanding of deception”. Cognition 13(1), 103–128.

Wellman, H. M., Cross, D., & Watson, J. (2001). Meta-analysis of theory-of-mind development: The truth about false belief. Child Development, 72, 655–684.

Wellman, H. M., & Liu, D. (2004). Scaling of Theory-Of-Mind Tasks. Child Development, 75(2), 523-541.