Belief Flexibility (BF) has been shown to maintain delusional conviction in patients with psychosis, and is a target of psychological intervention for delusions. However, it is unclear how BF responds to antipsychotic treatment. While BF has typically been measured in interview-based assessment, it is of interest whether moment-to-moment changes in BF can be measured reliably using experience sampling methodology (ESM).

Objectives Aims

To assess changes in BF during the first two weeks of antipsychotics, and to examine the validity of assessing BF using ESM.

Sixteen acute in-patients with delusions completed an ESM assessment 7 times a day on a Personal Digital Assistant over 14 consecutive days (see Table). Symptomatology, delusional dimensions, and BF were also measured in interviews on the first, seventh and fourteenth days.

Multilevel regression models revealed high internal consistency of the ESM items for BF, but low congruence between the ESM and interview measures of BF. Unexpectedly, patients with more flexibility at baseline (on one interview measure) reported increasing delusional conviction on ESM over 14 days (See Figure). On ESM, a higher momentary level of flexibility predicted an increase in conviction in the next moment.

The ESM data of BF were inconsistent with the interview measures and previous studies. The results challenge the validity of assessing BF with a self-report momentary measurement.

Table ESM items on Delusional Conviction and Belief Flexibility Item Response Delusional conviction −At this moment, to what extent do you believe this concern is true? 1 (not at all) – 7 (very much) Belief Flexibility − At this moment, to what extent do you think their aie other possible explanations for this concern? 1 (not at all) – 7 (very much) −At this moment, to what extent do you think you may be mistaken about this concern? 1 (not at all) – 7 (very much) − Since the last signal, have you noticed anything that makes you question this concern? 1 (not at all) 7 (very much)