The Antecedents - Behaviour - Consequences (ABC) model of behaviour change is a tool for understanding the ‘active ingredients’ that are contributing to maintain the behaviour that we want to change. The ABC model focuses on understanding the contingencies that shape someone’s behaviour by identifying what happens before (antecedents) and after the target behaviour (consequences) occurs. Once we understand what triggers the behaviour and how the consequences of the behaviour reinforce it, we can design interventions to modify the target behaviour. 

The ABC model originated from approaches that applied principles of learning theory to analyse and assess problem behaviours [23], and it focuses on how behaviour is shaped by the interaction between the different events that happen in our context, and which consequences effectively reinforce or punish it. It is underpinned by the concepts of classical conditioning, which explain how things that normally don’t evoque a response can become linked to things that do evoque a certain response, and instrumental conditioning, which explains how voluntary behaviour is affected by its consequences.

The antecedent refers to something that happens before the target behaviour and that triggers it. Antecedents can be external, such as a certain place, time of the day, a topic of conversation, a notification, a smell… or internal, such as a specific thought or an emotion. Consequences refer to what happens after the person does the target behaviour. Consequences can be positive or negative and they are essential because they impact the likelihood of the person continuing or ceasing to engage in the target behaviour. 

For example, we may identify eating fast food as a problematic behaviour (B) that we may want to reduce. By exploring what happens before we eat junk food, we may find that we eat junk food when we are feeling very anxious (A). After eating junk food, we feel more relaxed and content for some time (C). The reinforcing properties of the consequence (reducing the level of anxiety) will help maintain the problematic behaviour that we want to change. At this stage, a practitioner could suggest interventions to modify these contingencies. For example, using behavioural substitution we could try to do some other activity (e.g., going for a walk) when we are feeling very anxious.

This pattern of Antecedent - behaviour - Consequence does not only apply to health related behaviours. From a more product design perspective, we may want to ensure that we identify or design a specific trigger, and that the user receives a positive consequence after performing the desired behaviour.

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ABC tip 

To help you explore potential antecedents and consequences of the behaviour, you can use these prompts: 

Antecedents

What is the setting where the behaviour happens?

Does something happen in the environment?

Who is the person with?

Are there interactions taking place?

Any specific sensory stimulation? (temperature, light, noise…)

What time of day, month, special events/days… is it?

What might they be feeling or thinking?

Any unmet needs? (hunger, tiredness, boredom, anxiety…)

Consequences

What happens right after the target behaviour?

What happens long term?

How are others affected by the behaviour?

Does the behaviour seem to be immediately useful to the person?

✅ The ABC model is heavily supported by evidence.Studies on classical and instrumental conditioning, which underpinned the model, and other associated phenomena (extinction, stimulus generalisation, learned helplessness…) have been replicated numerous times, and they have been demonstrated in human and non-human animals (pigeons, rats, fish, dogs…) alike [24-26].

✅ Unlike other models, the ABC model explicitly recognises the key role of the environment in relation with behaviour. Changing the environment can shape behaviour. 

❌ Unlike other models, the ABC model doesn’t offer guidelines on intervention design and implementation.