The Role of Expectations in the Development of Intrusive Memories

Participants are asked to complete a pen-and-paper diary 7 days in a row, reporting on intrusive memories in reference to the trauma film. They are asked to state the number of intrusions per day; each day of the diary is labeled and split into three sections (morning, afternoon, evening), and they are asked to mark in a box in the appropriate section when they experienced an intrusion. For each intrusion, they indicate the quality of the intrusion (image, thought or both), the intensity of and distress caused by the intrusion both on a scale ranging from 0 ("not at all") to 10 ("extremely"), the content of the intrusion, and the situation in which the intrusion occurred. Intrusive memory frequency across 7 days are calculated, whilst higher sum scores represent more intrusions. Severity of intrusions are calculated by combining the average score of the intensity and distress scale across all intrusions, whilst higher values indicate higher intensity/distress of reported intrusions.

Participants are asked to respond 22 items in reference to the trauma film (e.g., "Pictures about the film popped into my mind.") by indicating how often each reaction occurred during the past seven days with respect to the film they watched last week. Items are rated on a 4-point-Likert-scale ranging from 0 ("not at all"), 1 ("rare"), 3 ("sometimes") to 5 ("often"). The IES-R consists of three subscales: "intrusion", "hyperarousal", and "avoidance". The total score (sum score for the total scale comprising the sum scores of all three subscales) is calculated ranging from 0 to 110 with higher values represent a worse outcome, i.e., higher total distress due to the trauma film in the past week. In addition, the sum score for the intrusion subscale is separately calculated ranging from 0 to 35 (Items 1, 3, 6, 9, 14, 16, 20) with higher values represent more intrusions due to the trauma film in the past week.

In the Intrusion Provocation Task (IPT), participants are presented with a ten-second long neutral still image from each of the film clips. Immediately afterwards for the next two minutes, they are allowed to think freely and report intrusions by raising a finger. The investigator counts how often the participant lifts his finger in the two minutes. The IPT intrusion score is calculated by the total frequency of intrusions, whilst higher values represent more intrusions.

The Appraisals of Intrusions Questionnaire is 25-item measure that assesses metacognitions of intrusive thoughts and memories. Participants rated the strength of each belief when they experienced their intrusive memories on a scale ranging from 0 (I didn't believe that at all.) to 100 (I was completely convinced that this was true.). Metacognitive appraisals are divided into four categories: "necessity of control", "external consequences", "psychological problem" and "negative self-evaluation". A total score is calculated, whilst higher values indicate more dysfunctional metacognitive beliefs.

Participants are asked in a self-report questionnaire to report for each day and each film clip the amount of time they spent actively processing the content of the film or intrusions associated to it, e.g., by intentionally thinking about it or by discussing it with other people. The participants are asked to rate how many minutes each day they have consciously dealt with the specific film clips or the memories of them. The scale ranges from 0 to 100 minutes in order to pre-define a lower and upper bound. The total score is calculated, whilst higher values indicate a better outcome.