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Page 1

Simulating personal future
events: Contributions from

episodic memory and beyond
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Citation Gaesser, Brendan James. 2014. Simulating personal future
events: Contributions from episodic memory and beyond. Doctoral
dissertation, Harvard University.

Citable link http://nrs.harvard.edu/urn-3:HUL.InstRepos:11744431

Terms of Use This article was downloaded from Harvard University’s DASH
repository, and is made available under the terms and conditions
applicable to Other Posted Material, as set forth at http://
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use#LAA

Page 2

Simulating personal future events:
Contributions from episodic memory and beyond






A dissertation presented


by


Brendan Gaesser


to


The Department of Psychology


in partial fulfillment of the requirements
for the degree of

Doctor of Philosophy
in the subject of

Psychology



Harvard University
Cambridge, Massachusetts


November 2013

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Figure 2.3. As the hippocampus was an a priori region of interest, activations are presented at a P
< 0.05 threshold corrected for multiple comparisons with a P=0.005 voxel-level threshold and
extent threshold of 17 voxels with the whole brain masked to only show voxels within the
bilateral hippocampus. L, left; R, right.


Table
 2.3
 
 

 
FMRI
 results:
 hippocampal
 masked
 

 
Brain
 Region
 
 
 
  peak
 MNI
 coordinate
 (x,
 y,
 z)
  Z-­‐score
 

 

 
Imagine
 >
 Re-­‐imagine
 

 
Anterior
 Right
 Hippocampus
  36,
 -­‐18,
 -­‐14
 
 
 
  3.25
 
 
Posterior
 Right
 Hippocampus
  24,
 -­‐28,
 -­‐10
 
 
 
  3.69
 
 
Posterior
 Left
 Hippocampus
  -­‐36,
 -­‐34,
 -­‐6
 
 
 
  3.69
 
 

 
(Imagine
 >
 Pleasant)
 >
 (Re-­‐imagine
 >
 Pleasant)
 hits
 only
 

 
Posterior
 Left
 Hippocampus
  -­‐36,
 -­‐36,
 -­‐6
 
 
 
  3.22
 
 

 

 
Note. Activations are significant at a p < .05 threshold corrected for multiple comparisons with a
p = .005 voxel-level threshold and extent threshold of 17 voxels. MNI, Montreal Neurological
Institute; L, left; R, right.

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Constructing future events: whole brain analysis.
 Contrasting activation during

imagining an event for the first time compared to re-imagining the same event (Imagine > Re-

imagine) revealed increased activity in the superior frontal gyri and regions in occipital and

temporal cortex related to visual/imagery processing (see Table 2.2, Figure 2.2B). We then

controlled for novelty- and encoding-related activity by subtracting activity associated with the

Pleasant condition and held subsequent memory performance constant (i.e. [Imagine > Pleasant]

> [Re-imagine > Pleasant], for hits only) This contrast showed activity in bilateral parietal lobes

as well as activity in regions related to visual/imagery processing, but now most prominently

observed was activity in the right superior frontal gyrus (see Table 2.2, Figure 2.2C). We also

examined increases in activity for repeated simulations (Re-imagine > Imagine). This contrast

revealed greater activity for re-imagining compared to imagining in the superior precuneus,

inferior frontal gyrus, and lateral temporal cortex (see Table 2.2).
 

Discussion

A distributed network of brain regions that includes the hippocampus is commonly

activated for remembering the past and imagining the future (Buckner & Carroll, 2007; Hassabis

& Maguire, 2007; Schacter et al., 2007; Spreng et al., 2009; Schacter et al., 2012). Moreover, the

hippocampus has also shown increased activity for imagining compared to remembering (e.g.

Addis et al., 2007; Weiler et al., 2010; Addis et al., 2011). It has been proposed that this

preferential hippocampal activity reflects the increased recombination demand associated with

integrating disparate episodic details into coherent scenarios (Schacter & Addis, 2007). The aim

of the present study was to evaluate this hypothesis by examining whether hippocampal activity

is sensitive to differences in constructive demand after controlling for both encoding- and

novelty-related activity. Our findings suggest that the hippocampal contributions to imagining

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Appendix


Supplementary Information

Methods. Participants who only provided partial data, inappropriate responses (e.g., by

providing responses for trials from the Imagine Helping and No Helping: Story conditions to a

question explicitly restricted to trials only from the Remember Helping condition), or neglected

to provide brief descriptions of what they generated for each task were not considered for data

analysis. Two participants were excluded from data analysis in Experiment 3: one participant

responded at ceiling for willingness to help across conditions, another participant indicated

feeling no emotional reactions at all. However, including these outlining participants did not

significantly affect the primary findings: (i) willingness to help was greater for the Imagine

Helping condition compared to the No Helping: Story condition (t(31) = 4.64, p < .001), (ii)

willingness to help was greater for the Remember Helping condition compared to the No

Helping: Story (t(31) = 3.29, p = .003), and (iii) willingness to help did not significantly differ

between Imagine Helping and Remember Helping conditions (t(25) = .12, p = .909).

Materials: Episodic vividness. To evaluate the extent that episodic vividness predicted

prosocial intentions to help, we included measures of episodic detail and coherence using the

following scales:

Detail

The imagined/remembered scene in your mind was? (1 = simple, 4 =moderately, 7 = detailed).

Coherence

The imagined/remembered scene in your mind was (1 = vague, 4 =moderately, 7 = coherent and

clear).

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Similarly, for the Estimate Helping condition, participants were asked:

Detail

The imagined media website in your mind was? (1 = simple, 4 =moderately, 7 = detailed).

Coherence

The imagined media website in your mind was (1 = vague, 4 =moderately, 7 = coherent and

clear).



In the second experiment, we included an additional measure of episodic vividness: event pre/re-

living.

How strongly did you experience the imagined/remembered event in your mind? (1= not at all, 4

= moderately, 7 = vividly, as if you were there)



Further supporting the detail and coherence findings, analyses revealed that the strength of pre-

living predicted willingness to help after imagining helping a person in need (r(28) = .54, p =

.002), and re-living predicted willingness to help after remembering a past experience related to

the circumstances of the present person in need (r(28) = .48, p = .008).

Materials: Example Stories. We provide below a few stories used to depict people in

need. Scenarios depicted a variety of situations, and the person in need was presented

anonymously so as to minimize possible gender or group membership effects. All of stories are

available from the authors upon request.

This person's dog has not returned home in the last 24 hours.

This person is locked out of their house.

While riding the train, this person is harassed by other passengers

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