Table 2.
Imagination inflation studies of childhood events
| Authors | Participants | Additional relevant conditions | % of events with increased belief ratingsa | Significant inflation effect | Mean belief/recollection increase on 8‐point scalea | Mean increase beyond scale midpointa |
|---|---|---|---|---|---|---|
| Garry et al. (1996) | 38 college students | (pre‐test ratings 1–4) 34% imagined 25% not imagined | Mean ratings not tested | |||
| Paddock, Joseph et al. (1998) Study 1 | 98 college students | (pre‐test ratings 1–4) 38% imaginedb 21% not imaginedb | Yes | |||
| Paddock, Joseph et al. (1998) Study 2 | 106 middle aged adults | No | ||||
| Paddock et al. (1999) | 94 college students | (pre‐test ratings 1–4) 47% imagined 35% not imagined | Yes | |||
| Heaps and Nash (1999) | 55 college students | Yes (1‐tailed test only) | Belief | No | ||
| 0.44 imagined | ||||||
| 0.18 not imagined | ||||||
| Clancy et al. (1999) | 12 women with recovered memories | Recovered memory status B/S | (pre‐test ratings 1–4) range: 25–19% imagined | Mean ratings not tested | ||
| 12 controls | 12% not imaginedb | |||||
| Horselenberg et al. (2000) Study 1 | 34 college students | No | Belief (1–7) | No | ||
| 0.37 imagined | ||||||
| 0.27 not imagined | ||||||
| Horselenberg et al. (2000) Study 2 | 45 college and high school students | Yes | Belief (1–7) | No | ||
| 0.51 imagined | ||||||
| −0.02 not imagined | ||||||
| Pezdek and Eddy (2001) | 43 college students, 32 older adults | Young versus old B/S | (pre‐test ratings 1–4) 39% imagined | No | Belief (pretest ratings 1–4) | No |
| 25% not imagined | 1.13 imagined | |||||
| 0.68 not imagined | ||||||
| Mazzoni and Memon (2003) | 72 college students | Improbable (skin) versus probable (tooth) event B/S; imagined versus exposed versus not imagined W/S | Yes | Belief range: | Probable event: | |
| 0.86–0.42 imagined | ||||||
| N/Ac Improbable event: No | ||||||
| −0.30 to −1.34 exposed/not imagined | ||||||
| Sharman et al. (2004) | 67 college students | Imagined versus paraphrasing W/S; 0, 1, 3 or 5 repetitions W/S | No | Belief b All < 1.00 | No | |
| Pezdek et al. (2006) | 145 college students | High versus low plausible events W/S | range: 38–21% imagined 28–23% not imagined | Yes (high plausible event only) | Belief range: 0.94–0.21 imagined | No |
| 0.39–0.22 not imagined | ||||||
| Sharman and Barnier (2008) | 78 college students | Positive versus negative events W/S | Yes: Belief and Recollection | (pre‐test ratings 1–4) | Yes: Belief No: Recollection | |
| Belief range: | ||||||
| 3.64–3.52 imagined | ||||||
| 2.22–1.90 not imagined | ||||||
| Recollection range: 3.09–2.90 imagined | ||||||
| 1.50–1.13 not imagined | ||||||
| Sharman and Scoboria (2009) | 60 college students | Belief analysis: moderate versus low event plausibility W/S; Recollection analysis: high versus moderate versus low event plausibility W/S | Yes: Belief and Recollection | Belief range: (pretest ratings 1–4) | Moderate and low plausibility events: | |
| 0.67–0.40 imagined | ||||||
| No: Belief | ||||||
| No: Recollection | ||||||
| 0.18–0.16 not imagined | ||||||
| High plausibility events: N/Ac | ||||||
| Recollection range: | ||||||
| (pre‐test ratings 1–8) | ||||||
| 1.14–0.08 imagined | ||||||
| 0.61 to −0.04 not imagined | ||||||
| von Glahn et al. (2012) Study 2 | 60 college students | Number of imagined details generated (0,3,6) W/S | Yes | Belief range: 0.30–0.21b imagined | No | |
| −0.04b not imagined | ||||||
| Bays et al. (2012) | 135 college students | Number of imaginings (0,1,5) W/S; High versus low plausibility events W/S | No: Belief and Recollection | Belief range: 0.13 to −0.08 imagined | No | |
| −0.18 to −0.33 not imagined | ||||||
| Recollection range: 0.34 to 0.04 imagined | ||||||
| −0.10 to −0.18 not imagined | ||||||
| Bays, Foley, and Zabrucky (2013) | 151 college students | Number of imaginings (0, 1, 5) W/S | No | Belief range: (pretest ratings 1–4) | ||
| 1.26–1.05 imagined | ||||||
| 0.69 not imagined | ||||||
| Marsh et al. (2014) Study 1 | 47 college students | Imagined from first versus third person perspective W/S | Yes (third person perspective only) | Belief range: 1.11–0.47 imagined | No | |
| 0.04 not imagined | ||||||
| Marsh et al. (2014) Study 2 | 64 college students | As for Study 1 | Yes (third person perspective only) | Belief range: 0.64–0.20 imagined | N/Ac | |
| −0.17 not imagined |
Cells left blank where relevant data not reported.
B/S = between‐subjects; W/S = within‐subjects.
a
Belief (confidence) and recollection ratings in listed studies are all on 1‐ to 8‐point scales unless otherwise specified; where ranges are given, means and percentages vary according to condition; scales include the following: Life Events Inventory (LEI: Garry et al., 1996) with authors' modified events; Autobiographical Beliefs and Memory Questionnaire (ABMQ: Scoboria et al., 2004).
b
Estimated from published figures.
c
N/A = not applicable as all mean pre‐test ratings are above or near midpoint.