An intentional introduction to the intentionality bias

    Central London. I am among a dozen of people queuing for the same bus. Following unwritten rules, we have formed a sinuous queue along the edge of the pavement. All of us need to get on that bus. I, for one, have an important presentation to give in 20 minutes and I’m already going through the slides in my head. Suddenly, the person next to me pushes me so that I lose balance and have to take a step back. In un-British fashion, I don’t apologies but give the guy the evil eye signalling he is being rude.

    Is that the only way I could have reacted? Probably not. For example, I could have noticed that the person almost fell over because of a heavy bag and could have smiled understandingly, but to do so I would have had to pay attention to my surroundings rather than my upcoming presentation. In this case, I didn’t think about it twice but jumped straight to the conclusion of having been pushed on purpose and, hence, responded with an evil look.

    We react differently to behaviour we think is intentional rather than accidental, hence, identifying and interpreting intentions is a vital aspect of social interaction. Intentional behaviour likely follows a purpose, which can either be beneficial or harming to us. An accidental action, in contrast, is less likely to happen again (as it was an “accident”) and therefore doesn’t pose as great of a threat to us. Additionally, intentional behaviour tells us more about a person’s goals, and depending thereon we might support or interfere with their actions.

    Considering the importance of identifying intentions in social interaction, it would only be plausible if evolution made as “intention-identifying-experts”, but as research suggests we are not as accurate as we might think: Not every ambiguous action (an action that could equally be done on purpose as by accident) has a 50/50 chance of being judged as accidental but we are biased towards judging them as intentional (e.g., Rosset, 2008; Moore & Pope, 2014). This tendency has been shown across the population, in children as well as adults (Rosset, 2007), which suggests that inferring intentionality is not primarily developmental but is inherent to our brain functioning. The evolutionary explanation for this bias could be that wrongly judging a behaviour as intentional is most of the time less costly than wrongly judging it as accidental (Moore & Pope, 2014).

    With the aim of forming a cognitive model of the intentionality bias, Rosset (2008) introduced a dual-process hypothesis, which says that behaviour is always judged as intentional (automatic stream), unless such judgment is inhibited by a more cognitively demanding stream that proposes an alternative cause. Simply put, by default we judge all actions as intentional. This explanation of the bias would fit into the idea of a wrong “intentional” judgment being less evolutionary costly than a wrong “unintentional” one. However, as of yet, it remains a theoretical model, applying cognitive neuroscientific methods could be a good way of testing this model.

    Cognitive processes or states affecting intentionality judgments might give us a hint. Rosset (2008) compared intentionality judgements of a speeded and unspeeded condition (i.e., high and low cognitive load) and found that participants showed an even higher intentionality bias in the speeded condition, which is – in accordance with the hypothesis - when they have less mental capacity “available” to engage in the non-automatic stream. Potentially, brain areas predominantly activated during times of high cognitive load are also involved in forming intentionality judgments. Based on results suggesting a relationship between the strength of the intentionality bias and schizophrenia and schizotypy (e.g., Peyroux, Strickland, Tapiero, & Franck, 2014; Moore & Pope, 2014), Moore and Pope put forward the idea that frontal lobe processes might play a key role in intentionality judgment formation. Schizophrenia is associated with frontal lobe dysfunction, hence, if frontal areas are involved in “accidental” judgments a stronger bias in people with schizophrenia or schizophrenia-like symptoms is unsurprising. 

    At the current state, cognitive neuroscientific research on the intentionality bias is still in its infancy and certainly no easy task to undertake (not the least because of the difficulty of establishing a paradigm that does not push people into judging a certain way). If we succeed in getting a clearer understanding of the neural correlates of the intentionality bias, this will not only add to our knowledge of the healthy “social brain” but also give us some conclusion of what might be an underlying cause for social interaction “going wrong” in bus-queuing scenarios like my own as well as psychiatric disorders. Identifying and interpreting others’ intentions is a key factor of social cognition and once again the way we feel we arrive at our conclusions might be further from the truth than thought.




Moore, J. W., & Pope,  a. (2014). The intentionality bias and schizotypy. Quarterly Journal of Experimental Psychology (2006), (June), 1–7.

Peyroux, E., Strickland, B., Tapiero, I., & Franck, N. (2014). The intentionality bias in schizophrenia. Psychiatry Research, 219(3), 426–430.

Rosset, E. (2007). Intentional until proven otherwise: Evidence of an explanatory bias in children and adults. Dissertation Abstracts International, 68, 2689.

Rosset, E. (2008). It’s no accident: Our bias for intentional explanations. Cognition, 108(3), 771–780.



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