The impact of the withdrawal of long-term antipsychotic medication prescribed to adults with intellectual disabilities on behavioural functioning has been investigated using a real-time direct observation methodology. Previous authors have reported a significant post-reduction difference in engagement in activity between the successful drug reduction and control groups. Method In the present study, sequential analysis of the relationship between staff:resident interaction and behavioural engagement was used to give a more precise measure of the extent to which user responsiveness is affected by drug withdrawal. Responsiveness was measured by calculating the likelihood of engagement occurring given the occurrence of staff interaction. This likelihood was represented by the statistic Yule's Q-value. Results High Yule's Q-value results pre- and post-baseline were found, indicating that clients were highly responsive to staff interaction. However, Yule's Q-value did not significantly increase following drug withdrawal. Conclusion The present study provides no evidence of greater responsiveness following the withdrawal of psychotropic medication.