CACTIS Tool v1.9.1

Design behaviour change interventions, step by step

CACTIS takes you from a behavioural goal, through a COM-B diagnosis, to a set of behaviour change techniques. It then builds a structured prompt you can give to Claude or another AI tool to draft a strategy.

You can switch at any time with the switch at the top of the page, without losing anything you have entered.

1
Specify the problem
The behaviour, who it involves and where.
2
Diagnose with COM-B
Rate 27 factors; CACTIS sets each one’s priority.
3
Select techniques
Choose BCTs for your High priority targets.
4
Copy your prompt
Paste it into an AI tool to draft a strategy.

More information: the two modes, saving your work, citing CACTIS and the BCT reference workbook

🗣️ Standard and Communications modes Experimental
CACTIS can be used in two modes, chosen on this page or with the switch at the top of every page. Standard mode supports the design of any behaviour change intervention. Communications mode sets the problem as designing a communication strategy: Step 1 adds an audience analysis; Step 2 marks COM-B targets that a communication strategy cannot address directly; Step 3 offers only BCTs with a role in a communication strategy — those a message can deliver, those the communication strategy can prompt people to do for themselves, and other intervention components it can signpost; Step 3b adds message design (communication functions, tone, source and delivery); and Step 4 shows Think, Feel, Act targets and generates a prompt for drafting messages. Communications mode is experimental and offered as a trial version: it is still being developed and tested, and its classification of BCTs, prompts and outputs may change. You can switch at any time without losing anything you have entered. To open CACTIS directly in Communications mode, use com-b.org/cactis?mode=comms.

💾 Saving your work: Your work is saved automatically in this browser. Use File › Save to file at the top of the page to keep a permanent copy, and File › Restore from file to open it again later or on another computer.

📄 Open source & licensing: This tool is open source and free to use. Please note that CACTIS is presented as is and users take responsibility for any and all consequences of its use. Use of CACTIS should be acknowledged in any reports along the lines of ‘The CACTIS tool version 1.9.1 (see https://com-b.org/cactis) was used in the development of this intervention. The authors of CACTIS bear no liability for any adverse consequences of its use.’

📊 BCT Reference Workbook
Download the full BCT mapping reference as an Excel workbook — includes the complete BCT reference list, a de-duplicated list of BCTs, a list of BCT × Intervention Function combinations, the COM-B × Intervention Function mapping matrix, intervention function definitions, a COM-B quick reference, and the Communications mode classification of each BCT.

Step 1: Specify the Problem

Be precise and observable. Use the ? buttons for guidance and examples.

In Communications mode the problem is set as designing a communication strategy. Describe the behaviour the communication strategy should change, the audience it is aimed at, where they will encounter it and any constraints already decided, then complete the audience analysis below.

🎯 Behavioural Goal

Describe the specific behaviour you want to promote or reduce. Be precise: what is the behaviour, in what direction, how much, and by when?

👥 Target Population, Group or Person

Describe who the intervention is aimed at. Include relevant characteristics such as age, health status, geography, or setting.

📍 Intervention Setting(s)

Where will the intervention take place? Include all relevant settings.

⚙️ Implementation and Delivery Constraints (optional)

Optional. Describe any constraints already in place regarding how the intervention will be delivered — e.g. mode of delivery, policy options, budget, timing. Leave blank if none.

🔎 Audience Analysis

For each dimension, indicate where your audience sits. These features shape how messages should be designed and are passed to the message prompt in Step 4. Leave any you do not know as ‘Not specified’.

Audience preconceptions and other notes

What does the audience already believe or expect about the behaviour? Note any misconceptions, competing narratives, or segments that may need different approaches.

Step 2: Identify COM-B Targets

Rate each factor for room for improvement and strength of evidence; CACTIS sets the priority. For High priority targets you can add the evidence and rationale. Click a heading to collapse a section.

0 of 27 rated

In Communications mode, complete the diagnosis for all targets. Targets marked Messages can only signpost for this target cannot be addressed directly by a communication strategy: if they are a high priority, other intervention components will be needed, which the communication strategy can publicise.

Step 3: Select Behaviour Change Techniques

For each High priority COM-B target, click the + button under each Intervention Function to select one or more BCTs. You can select multiple BCTs per cell.

For each High priority COM-B target, click the + button under each Intervention Function to select one or more BCTs. Only techniques with a role in a communication strategy are offered: those a message can Deliver, those the communication strategy can Prompt people to do for themselves, and components delivered by other means that the communication strategy can Signpost.

COM-B Target	Priority	Education	Persuasion	Incentivisation	Coercion	Training	Rule-making	Env. Restructuring	Modelling	Enablement

🗣️ Message Design

Choose the communication functions and tone the messages should use, and note the intended source and delivery. These shape the message prompt in Step 4. All fields are optional.

Communication functions

What should the messages be trying to do?

Communication tone

The emotional character or ‘voice’ of the messages.

Source

Who should the messages come from or be attributed to, and how authoritative and trustworthy is that source for this audience?

Channels and delivery

Channels, timing and frequency of exposure, and format (e.g. text, image, audio, video, interactive).

Step 3b: Detail the Selected BCTs

For each BCT you selected, record the rationale for selecting it and what it could look like in the communication strategy. For signposted components, describe how the communication strategy should refer to them and who delivers them. Both fields are optional and feed into the message prompt in Step 4.

For each BCT you selected, record the rationale for selecting it and what the BCT combination could or should look like in practice. Use the ? buttons for guidance on what each field requires and where the information may come from. Both fields are optional and feed into the LLM prompt in Step 4.

Step 4: Your LLM Prompt

Copy this prompt and paste it into Claude or another AI tool to generate a draft intervention strategy.

Download decision record

A formatted Word document with everything entered: the problem definition, full COM-B assessment, selected BCTs with their implementation detail, and the generated prompt.

A formatted Word document with everything entered: the communication brief and audience analysis, full COM-B assessment, Think, Feel, Act targets, selected BCTs with their detail, message design and the generated prompt.

Think, Feel, Act Targets

High and Medium priority COM-B targets translated into what the communication strategy wants the audience to think, feel and do.

Summary of your inputs

Selected BCTs

About CACTIS

CACTIS is developed by the Unlocking Behaviour Change CIC (unlockingbehaviourchange.com) with support from The Public Health Wales Behavioural Science Unit. It undergoes continual development in the light of evidence, theory and user experiences.