Inclusion Criteria:  Aged: 18-69 (at time of enrollment to cohort study) Able to speak and read study materials in Icelandic or English Willing to be contacted remotely and having access to a smartphone or computer Experienced intrusive memories in past month (PCL-5 item 1 score is ≥ 2) Experienced 2 or more intrusive memories of a traumatic event in the past week Willing to monitor intrusive memories in everyday life Willing and able to complete remote study sessions  Exclusion Criteria:  Suicide risk indicated in the initial assessment (response of 'nearly every day' to item 9 on PHQ-9) and by responses on MINI during follow-up telephone risk assessment