Table 4.

Summary of Findings of Studies Examining Post-Event Predictors Included in Systematic Review

Study	Sample	N	Study Design		Independent Variable(s)	Intrusion Variables Reported (DVs)			Intrusion Assessment Timing			Intrusion Measurement			Main Findings	Effect Size (if reported)
			Ran	Pros		Freq	Distress	Other	During	7 Day	Other	Monitor	Diary	Other
Appraisals and Biases
Hagenaars & Arntz (2012)	University (excluded psychopathology, MVA experience)	76	✔	✔	Imagery rescripting vs. reexperiencing vs. positive	✔				✔			✔		Imagery rescripting → lower intrusive memories than reexperiencing and positive conditions	η2 = 0.11 (overall)
																d = 0.57 (rescripting vs. positive)
																d = 0.87 (rescripting vs. reexperiencing)
Kleim et al. (2012)	MVA or assault survivors	221	✔	✔	Processing advantage for trauma-related stimuli: ID rate of trauma-relevant pictures minus neutral ID rate	✔				✔				✔ Intrusive memory Interview	Higher processing advantage for trauma-related stimuli → more intrusive memories	r = 0.14
Newby et al. (2014)	Community (mildly depressed; excluded bipolar depression)	60	✔	✔	Positive appraisal vs. education vs. control	✔	✔			✔			✔	✔ IMI	Education → greater reductions in intrusive memory distress (IMI) compared to control; nonsig. difference between education and positive appraisal	d = 0.89 (education vs. control)
															Nonsig. association w/frequency via diary
Verwoerd et al. (2009)	Undergrad	36		✔	RSVP difference score	✔				✔			✔		Bias toward trauma-relevant information → more intrusive memories
Woud et al. (2012)	University	76	✔	✔	+ vs. – reappraisal training	✔				✔			✔		+ reappraisal training → lower intrusive memories	d = 0.49
															Nonsig. association between condition and intrusive memory distress
Rumination
Ball & Brewin (2012)	University (moderate-to-high ruminators) (Excluded treatment history, trauma history, MVA experience)	60	✔	✔	Film related rumination vs. non-film related vs. no task	✔	✔	✔		✔			✔		Rumination conditions → more intrusive memories, greater # of days w/ intrusive memories	d = 0.59 (intrusive memory freq)
															Nonsig. association with intrusion-related distress, reliving, or vividness	d = 0.79 (days with intrusive memories)
Ehring et al. (2009)	University (excluded psychosis, depression, suicidality, trauma history)	83	✔	✔	Abstract rumination vs. concrete thinking vs. distraction	✔	✔	✔	✔		✔ 3 days			✔ Intrusive memory Questionnaire	Distraction → more intrusive memories after reminders	η2 = 0.10 (distraction vs. abstract + concrete after reminders)
															Nonsig. effect on intrusive memory freq after manipulation or 3-day follow-up
															Nonsig. differences b/w abstract and concrete
															Nonsig. effects on vividness and distress
Ehring et al. (2009)	University (excluded psychosis, depression, suicidality, trauma history)	51	✔	✔	Rumination vs. distraction	✔	✔	✔	✔					✔ Intrusive memory Questionnaire	Rumination → more intrusive memories pre- to post-manipulation	η2 = 0.21 (pre-post* condition interaction; frequency)
															Distraction → greater reductions in intrusive memory distress pre- to post-manipulation, and post-manipulation to post-provocation task	η2 = 0.25 (pre-post* condition interaction; distress)
																η2 = 0.25 (post-manipulation – post-provocation; distress)
Kubota et al. (2015)	University (excluded psychopathology)	90		✔	PTQ-S	✔	✔		✔	✔		✔			State rumination did not significantly mediate relationship between depression and intrusive memory freq when trait rumination controlled for	k2 = .15 (indirect effect of state rumination on intrusive memory distress)
															Did mediate relationship between depression and intrusive memory distress
Laposa & Rector (2012)*	University (excluded psychopathology, treatment history history)	91		✔	ARQ RIQ	✔				✔			✔		Higher rumination in response to intrusive memories → more intrusive memories even after controlling for depression	r = .38
															Nonsig. association between anxious rumination and intrusive memories
Santa Maria et al. (2012)	University (excluded depression, suicidality, psychosis, sexual assault history)	57	✔	✔	Abstract vs. concrete rumination; RRS; PTQ	✔	✔	✔	✔		✔ 1 and 3 days post			✔ 3 items from IES	Abstract → smaller decrease in intrusive memories pre- to post-manipulation and pre-to end of session even after controlling for trait rumination	d = 0.57 (pre-to post)
																d = 0.60 (pre to 3 days post)
															Nonsig. effects on vividness and distress
Williams & Moulds (2007a)*	Undergrad	57	✔	✔	Low vs. high dysphoria groups; Analytical vs. experiential vs. distraction	✔	✔		✔			✔			Nonsig. associations between IVs and DVs
Williams & Moulds (2010)	Undergrads w/ dysphoria	77	✔	✔	Analytical rumination vs. distraction		✔	✔	✔					✔ IMI	Analytical → higher intrusive memory distress, intrusion-related sadness, intrusive memory negativity even after controlling for trait rumination
Zetsche et al. (2009)*	Community (excluded depression, blood phobia, trauma history)	101	✔	✔	Rumination vs. memory integration vs. control	✔			✔	✔			✔	✔ IMQ	Nonsig. associations between IVs and DV during session and via diary
Suppression/Cognitive Load
Aikins et al. (2009)	Combat veterans	43		✔	PTSD vs. trauma exposed vs. non-trauma exposed	✔		✔	✔			✔			PTSD → more post-suppression intrusive memories compared to other groups
Bomyea & Amir (2011)	Undergrad	50		✔	Working memory task: high vs. low inhibitory control (HIC; LIC) Monitor vs. suppression vs. post-suppression monitor period	✔			✔			✔			HIC → fewer intrusive memories during suppression and post-suppression monitoring	d = 0.51 (HIC vs. LIC suppression)
																d = 0.51 (HIC vs. LIC, post-suppression monitoring)
Bomyea & Lang (2016)	Sexual assault survivors with PTSD	42		✔	OSPAN task score Thought suppression task-reactivity questionnaire Monitor vs. suppression vs. post-suppression monitor period	✔			✔			✔			Thought regulation strategies → more intrusive memories, moderated by executive functioning performance; those with poorer executive functioning used more thought reg. strategies
															Nonsig. direct relationship between executive functioning and intrusive memories
Davies & Clark (1998b)	Undergrad (excluded treatment history, history of fire involvement)	32	✔	✔	Traumatic vs. neutral thought content Suppression vs. monitoring instructions	✔			✔			✔			Suppression → fewer intrusive memories during first period for both neutral and trauma film
															Suppression → more intrusive memories during post-suppression monitor for traumatic but not neutral film-related intrusive memories
Geraerts et al. (2010)	Undergrad	87	✔	✔	Negative vs. neutral autobiographical event Suppression vs. monitoring instructions	✔			✔			✔			Suppression → fewer intrusive memories during first period and during AMT regardless of event valence	d = 0.44 (first period suppression vs. control)
																d = 0.42 (AMT suppression vs. control)
Gillie et al. (2015)	Undergrad	142	✔	✔	Suppression vs. monitor instructions HRV	✔			✔			✔			Suppression → fewer intrusive memories during first period compared to monitor
															Suppression → greater decline in intrusive memories from first to second period but not from first to third
															Higher HRV → greater declines in intrusive memories from first to second and first to third period in suppression but not control condition
Guthrie & Bryant (2000)	Trauma-exposed (mixed trauma)	40	✔	✔	Suppression vs. non-suppression instructions; ASD vs. no ASD	✔					✔ (3 separate 24 hr monitor periods)	✔			ASD → more intrusive memories regardless of suppression condition
															Suppression condition → more intrusive memories during third monitor period
Harvey & Bryant (1998)	MVA survivors	48	✔	✔	Suppression vs. non-suppression; ASD vs. no ASD	✔			✔			✔			ASD → more intrusive memories regardless of suppression condition for all three monitor periods
															Suppression condition → more intrusive memories during third monitor period than non-suppression
Harvey & Bryant (1999)	University	96	✔	✔	Distressing vs. neutral film Suppression vs. control High vs. low anxiety (via STAI)	✔			✔			✔			Distressing film viewers → more intrusive memories after period 1 than neutral film viewers
															High anxiety → more intrusive memories after period 1 than low anxiety in nonsuppression condition only
															Suppression → more intrusive memories after period 2 than nonsuppression in low anxiety group only
Nixon et al. (2008)	Trauma-exposed (mixed trauma)	56		✔	White bear vs. trauma-related intrusive memories; ASD vs. no ASD	✔			✔			✔			ASD → more trauma-related and white bear intrusive memories during suppression period than group w/o ASD	d = 0.67 (ASD vs. no ASD trauma-related intrusive memories)
																d = 0.58 (ASD vs. no ASD white bear)
Nixon et al. (2009a)	University	80		✔	Suppression + cognitive load vs. cognitive load only vs. suppression only vs. control	✔	✔		✔	✔		✔	✔		Suppression + cognitive load → more intrusive memories compared to other conditions via 7 day diary
															Nonsig. effect of condition on intrusive memory distress
															Nonsig. effect of condition on intrusive memory freq during in-session monitor period
Nixon et al. (2009b)	University	120		✔	Suppression + cognitive load vs. hypervent. + suppression vs. block rehearsal + suppression vs. suppression vs. no task control	✔		✔	✔	✔		✔	✔		All experimental conditions → significantly shorter intrusive memory duration than no task control (in session)
															Nonsig. associations between IVs and intrusive memory variables via diary
Nixon et al. (2016)	Trauma-exposed (mixed trauma)	56		✔	Cognitive load vs. no cognitive load ASD vs. no ASD	✔			✔			✔			ASD → more intrusive memories than non-ASD overall ASD + cognitive load → more intrusive memories following suppression compared to ASD w/o cognitive load	d = 0.90 (ASD vs. non-ASD overall)
																d = 0.63 (ASD w/ and w/o cognitive load)
Onden-Lim & Grisham (2012)	Undergrad (excluded BDD diagnosis)	92	✔	✔	Suppression vs. monitor instructions; BICI	✔	✔	✔	✔			✔			Nonsig. association between body image concern and intrusive memory frequency
															Nonsig. differences between conditions in intrusive memory vividness or perspective
															Supression → shorter intrusive memory duration than monitor
															Higher body image concern → increased intrusive memory vividness
Rosenthal & Follette (2007)	Assault survivors	61	✔	✔	Suppression vs. monitoring instructions Lab vs. natural environment	✔	✔		✔		✔ 24 hr, 48 hr	✔			Nonsig. associations between conditions and intrusive memory freq during in-session monitoring	d = 0.70 (monitor vs. suppress 24 hr post)
															Nonsig. differences in intrusive memory freq between conditions in natural environment 24 & 48 hr post
															Monitor → more intrusive memory distress during 24 hr post
															Nonsig. differences in distress 48 hr post
Shipherd & Beck (2005)	MVA survivors	55	✔	✔	MVA vs. neutral task Suppression vs. monitor instructions PTSD vs. no PTSD	✔			✔					✔ Written thought listing	MVA task → more target thoughts than neutral task regardless of PTSD diagnosis
															PTSD → more target thoughts than no PTSD in MVA task during post-suppression monitoring (rebound effect)
															Nonsig. differences in target thoughts between diagnostic groups during neutral task
Shipherd & Beck (1999)	Sexual assault survivors	36		✔	Suppression vs. expression instructions PTSD vs. no PTSD	✔		✔	✔					✔ Written thought listing	PTSD → more intrusive memories during post-suppression monitor period than no PTSD group (rebound effect)
															PTSD → lower thought controllability during suppression than no PTSD
Williams & Moulds (2007)	University	97	✔	✔	Suppression vs. expression of film-related thoughts (2 phases of each) Mildly depressed vs. non-depressed	✔	✔	✔	✔			✔			Nonsig. effect of depression group on intrusive memories
															Suppression 1 → more intrusive memories than suppression 2
															Nonsig. rebound effect between expression 1 and expression 2 phases
															Nonsig. effect of depression group on intrusive memory duration or distress
Post-Event Processing/Consolidation
Bryant et al. (2013)	University	78	✔	✔	Cold pressor task vs. warm water control sAA and cortisol levels Negative vs. neutral images	✔					✔ 2 days post			✔ 3 items from IES	High stress → more intrusive memories of negative images than low stress
															Interaction of cort + sAA → more intrusive memories in men only
Das et al. (2016)	Community (excluded psychopathology, drug use, trauma history)	50	✔	✔	Nitrous oxide vs. placebo	✔				✔			✔		Nitrous oxide → more rapid intrusive memory decrease (day 1 to 2 and 1 to 3)
Holmes et al. (2009)	Community	40	✔	✔	Visuospatial vs. no post-film task	✔			✔	✔		✔	✔		Visuospatial → fewer intrusive memories 10 min post-film
															Visuospatial → fewer intrusive memories via 7 day diary
Holmes et al. (2010)	University/Community (excluded treatment history)	60	✔	✔	Visuospatial vs. verbal vs. no post-film task	✔				✔		✔	✔		Visuospatial → fewer intrusive memories than no task 10 min post	d = 0.70 (visuospatial vs. no task via diary)
															Nonsig. effect of condition on intrusive memory freq between verbal and no task
															Visuospatial → fewer intrusive memories than no task and verbal conditions via diary	d = 1.21 (visuospatial vs. verbal via diary)
															Verbal → more intrusive memories than no task via diary	d = 0.62 (verbal vs. no task via diary)
Holmes et al. (2010)	University/Community (excluded treatment history)	75	✔	✔	Visuospatial vs. verbal vs. no post-film task	✔				✔	✔ 4 hr post-film	✔	✔		Visuospatial and verbal → fewer intrusive memories 4 hr post-film compared to no task	d = 0.70 (visuospatial vs. verbal via diary)
															Visuospatial → fewer intrusive memories compared to verbal and no task via diary
															Nonsig. difference on intrusive memories between verbal and no task via diary	d = 0.62 (visuospatial vs. no task via diary)
Kindt et al. (2008)*	Undergrad (excluded history of physical or xexual abuse)	42	✔	✔	Data-driven vs. conceptual post-film instructions	✔			✔					✔ VAS	Data-driven → more intrusive memories compared to conceptual	η2 = 0.08
Kleim et al. (2016)	Community (excluded psychopathology and exposure to interpersonal trauma)	65	✔	✔	Sleep deprivation vs. normal sleep	✔	✔			✔			✔		Normal sleep → fewer and less distressing intrusive memories
Krans et al. (2009)	Undergrad	52	✔	✔	Recognition memory test vs. no memory test	✔	✔			✔			✔		Recognition test → fewer intrusive memories	η2 = 0.11
															Nonsig. effect on intrusive memory distress
Luo et al. (2013)*	Undergrad	92	✔	✔	“What” vs. “why” processing	✔					✔ 2 day diary		✔		“Why” → fewer intrusive memories than “what” condition
Porcheret et al. (2015)	University	42	✔	✔	Sleep deprivation vs. normal sleep	✔	✔				✔ 6 day diary		✔		Sleep deprivation → fewer intrusive memories during first two-day period
															Nonsig. effect of sleep on intrusive memory distress
Tabrizi & Jansson (2016)	Undergrad	41	✔	✔	Visuospatial vs. phonological loop vs. executive processing vs. no task control Auditory vs. visual intrusive memories	✔				✔			✔		Executive processing → fewer auditory intrusive memories compared to no task and visuospatial	d = 1.13 (executive processing vs. no task)
															Nonsig. difference in auditory hallucinations between phonological loop and other conditions	d = 1.03 (executive processing vs. visuospatial)
															Nonsig. effect of condition on visual intrusive memory freq
Memory Reconsolidation
James et al. (2015)	University/Community	52	✔	✔	Reactivation + visuospatial vs. no reactivation no task	✔				✔			✔	✔ IPT	Visuospatial + reactivation → fewer intrusive memories both via diary and IPT	d = 1.14 (intrusive memory freq)
															Visuospatial + reactivation → more rapid intrusive memory decrease
James et al. (2015)	University/Community	72	✔	✔	Reactivation + visuospatial vs. reactivation only vs. visuospatial only vs. no reactivation no task control	✔				✔			✔		Visuospatial + reactivation → fewer intrusive memories than visuospatial only, reactivation only, and no task control	d = 0.84 (visuospatial + reactivation vs. visuospatial only)
															Reactivation + visuospatial → more rapid intrusive memory decrease compared to other three conditions	d = 1.11 (visuospatial + reactivation vs. reactivation only)
																d = 1.00 (visuospatial + reactivation vs. no task control)
Marks & Zoellner (2014)*	Undergrad	148	✔	✔	Pre-extinction vs. post-extinction vs. no retrieval cue	✔	✔				✔ 24 hr post-extinction			✔ Phone Assessment	Pre-extinction → more intrusive memories than no retrieval cue when controlling for peak distress during acquisition	d = 0.62
															Nonsig. effect of condition on intrusive memory distress
Vantage Perspective
Luo et al. (2013)*	Undergrad (excluded serious MVA experience)	93	✔	✔	First-person vs. third-person vantage perspective	✔		✔			✔ 2 days		✔		Nonsig. effect of vantage perspective on intrusive memory frequency, level of intrusive memory realism, or severity of intrusive memories
Williams & Moulds (2008)	Undergrad	134	✔	✔	Field vs. observer perspective		✔	✔		✔				✔ IMI	Switch from field to observer → decreased intrusive memory vividness and distress
Retrieval Stress / Distress
Cheung et al. (2015)*	Undergrad	63	✔	✔	Reactivation + stressor vs. reactivation + control vs. no reactivation + stressor	✔					✔ 5 days			✔ 3 items from IES	Reactivation + stressor → more intrusive memories than control conditions
															Cortisol increase following stressor → more intrusive memories in reactivation + stressor condition only
Hopwood & Bryant (2006)	Trauma-exposed (mixed trauma)	60	✔	✔	Hyperventilate vs. normal breathing instructions ASD vs. no ASD	✔			✔			✔			ASD → more intrusive memories during hyperventilation compared to baseline	η2 = 0.13 (overall group × condition × time)
															Non-ASD → fewer intrusive memories during hyperventilation compared to baseline
Schooler et al. (1999)	Plane crash survivors	118		✔	Frequency and distress of intrusive memories 2 wks post-trauma	✔	✔				✔ 6, 9, and 12 mo post-trauma			✔ ITQ	Presence of uncued intrusive memories at 2 wks → more intrusive memories at 6, 9, 12 mos
															More intrusion-related distress → more intrusive memories at 6, 9, and 12 mos

Study Quality: “Ran” = randomized, “Pros” = prospective; PTQ-S: Perseverative Thinking Questionnaire-State Version; ARQ: Anxious Rumination Questionnaire; RIQ: Response to Intrusions Questionnaire; RRS: Ruminative Response Subscale of Response Style Questionnaire; OSPAN: Operation span; HRV: Heart rate variability; ASD: Acute Stress Disorder; BICI: Body Image Concern Inventory; sAA: Salivary alpha amylase; IMI: Intrusive Memory Interview; IES: Impact of Event Scale; IMQ: Intrusive Memory Questionnaire; VAS: Visual Analogue Scales; IPT: Intrusion Provocation Task; ITQ: Intrusive Thoughts Questionnaire

^*Study included multiple times in table due to presence of multiple predictors of intrusions