Simple Cognitive Task After Trauma

Number of intrusive memories of traumatic event recorded by participants in a diary daily (morning, afternoon, evening and night) for 7 days

Number of intrusive memories of traumatic event recorded by participants in a diary daily (morning, afternoon, evening and night) for 7 days

Full scale is a 22-item self-report measure that assesses subjective distress after a traumatic events. Items are rated on a 5-point scale ranging from 0 ("not at all") to 4 ("extremely"). The IES-R yields a total score (ranging from 0 to 88) and subscale scores are calculated for the Intrusion, Avoidance, and Hyperarousal subscales summed. Higher scores indicate worse outcome. Our secondary outcome measure is the Intrusion subscale.

The HADS is a fourteen item scale. Seven of the items relate to anxiety and seven relate to depression. Each item on the questionnaire is scored from 0-3 and this means that a person can score between 0 and 21 for either anxiety or depression. Higher scores indicate worse severity.

Measures the perception of stress and the degree to which situations in one's life are appraised as stressful. The 14 items aims to assess how unpredictable, uncontrollable, and overloaded respondents find their lives. The items are rated on a 5-point scale ranging from 0 ("never") to 4 ("very often") and summed to a total score of 56. Seven items concerns positive experiences and are hence reversed in scoring. Higher scores indicate worse severity.

The Work & Social Adjustment Scale is a simple 5-item measure of general social impairment which grew out of a study of change during psychotherapy. The maximum score of the WSAS is 40, lower scores are better.

22 bespoke items including questions about study participation e.g. how burdensome was it to participate in the study?" rated on 9-point scale from 1 (never) to 9 (always); and those about what has happened since the study with a yes/no response e.g. have you had any psychological or medical treatment since our last contact; and items with a free text response field e.g. do you have any comments about what it was like to take part in the study.

Observation and qualitative interviews with participants, study team and staff regarding implementation of the procedures

5 item questionnaire (11 item scale from 0 to 10) that rates to what degree the participants finds the intervention credible. High scores indicate greater credibility. A free text response field about activities engaged in during the assigned condition.

A single item measuring perceived health status on a seven-point scale (from very good to very bad). High scores indicate good outcomes.

Two self rated items: Item 1 measures the extent of being troubled by poor sleep in the last month on a 5 point scale (from not at all to very much), and item 2 measures the number of nights in the week with sleep problems on 5 point scale (from 0-1 to 5-7 nights). Each 5-point scale is reverse scored (0 - 4) then summed. Possible total scores ranges from 0 - 8, with higher values indicative of better sleep.

Adverse events and potential side effects associated with intervention

7 self rated bespoke items measuring characteristics and sensory modality of intrusive memories: 1 self rated question regarding the presence and the extent of each of 7 sensory modalities in the intrusive memories (visual, auditory, tactile, somatic, olfactory, taste, and other sensations) measured on a scale from 1 (none) to 5 (extreme). 3 self rated items measuring the level of distress, vividness or disruption (functional impairment) associated with the intrusions (11 point scales from 0 to 10). High scores indicate higher level of distress/vividness/disruption.

Section H of MINI 7.0.0 (a short symptom interview) will be assessed at follow-ups to assess current symptoms of posttraumatic stress disorder. Section H consists of a minimum of 1 and maximum of 19 items, which continue depending on response to previous question). Higher scores indicate worse symptoms