In probability there is a concept known as the ‘event space’, which is defined as all possible events associated with an experiment or happening, the combined probabilities of which add up to one. For example, for a normal die, the event space contains the six numbers that can be rolled and the probability of rolling at least one of those six is one (irrespective of whether it is a fair die or whether some numbers are more likely to come up than others).
An equivalent concept in behavioural science is the ‘options space’, which is all the potential behavioural outcomes within a particular context. This can be further divided into an ‘objective’ options space and a ‘perceived’ options space. For example, if you have an argument at work, the objective options space contains all the possible responses including having a discussion about it, complaining to HR, resigning, and verbally or physically attacking the other person. While the objective options space may be similar for lots of people, they may have very different perceived options spaces. Some people might think about resigning but conclude that it isn't worth it (ie it is part of their perceived options space but they choose not to take that option). For others, the thought of resigning might not even occur to them, ie it is part of their objective option space but it isn't part of their perceived options space so they don't even consider it or think through the pros and cons.
One area where this distinction seems particularly important is in terms of the history of violence. Most people in the modern world wouldn't consider responding to an argument by being violent, so much so that the question ‘what stopped you being violent in that situation’ wouldn't even make sense. They couldn't talk about their motivation or decision-making process because being violent just isn't within their perceived options space. They have so fully absorbed the cultural norm of not being violent, they can't really conceive of it as an option. This is almost certainly very different to the situation 500 years ago, when violence seemed to be much more common.
For researchers, the concept of an options space is useful because it can help identify barriers and enablers that don't appear in traditional behavioural models. It can also potentially help intervention developers as finding ways to bring certain behaviours into the options space or exclude them from it, could be an important and powerful element of a behaviour change strategy.
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