Memory for Actions: A two-way mirror?
Nicholas Lange, Timothy J. Perfect & Patric Bach, Plymouth University
BACKGROUND
Confusing the sources of events or items has been observed in both the action and verbal
domain, but domains differ in the proposed causes and characteristics of this confusion.
verbal domain
• Source confusion is bidirectional, i.e. misattributions
both towards (unconscious plagiarism) and away from
the self (Perfect et al., submitted)
• proposed to result when contextual cues allowing
inference of the source of an idea are not or cannot be
used at retrieval  Source Monitoring account
action domain
• Source confusion is unidirectional, i.e. misattributions
towards the self (observation inflation, Lindner et al., 2010 )
• proposed to result from the creation of matching motor
representations for both action execution and observation
via mirror neuron network activation in the observer’s
motor system  Action Simulation account
Do characteristics of source misattributions differ between domains, i.e. bidirectionality of source errors?
Does an action simulation account need to be invoked in the action domain?
- 38 participants in pairs
METHOD - 4 exemplars/participant generated for 15 shape cues
Generation Phase: secondary tasks during observation of partner’s generation:
1. no secondary task, 2. a simple motor task (medium load, no action planning),
3. visual-spatial working memory task (high load, action planning)
Retrieval Phase: 1 day delay, free recall of own or partner’s examples
Simulation: estimation of chance performance in source and intrusion errors by
matching a random partner to each participant while target of participants’
recall (self or partner) was not varied, resulting in stable correct rates
1. Source Monitoring account: source misattributions
PREDICTIONS
in the recall partner task
2. Source Monitoring and Action Simulation accounts: a. increase of other-plagiarism in generation phase and
b. decrease in correct recall in recall partner task under secondary task load
3. Secondary task load leads to differing predictions in both accounts for source confusion in recall own
task: - Source Monitoring: increase of source errors (distraction  inability to encode source cues)
- Action Simulation: decrease of source errors (motor system occupied  inability to encode items)
RESULTS
generation phase
retrieval phase
u
* Error bars: 95% confidence interval
u
1. * p<.001
(from 0)
u
2a. p=.078
(linear contrast, p=.02)
3. p=.48
2b. * p=.048
(linear contrast, p=.04)
* Error bars: 95% confidence interval
While secondary motor task load during action observation affected performance at
DISCUSSION encoding (2a.) and retrieval (2b.), it crucially did not affect source error rates (3. ), contrary to
Action Simulation and Source Monitoring predictions. Observed source misattributions of own actions away from
the self (1. ) cannot be accounted for by an Action Simulation account, however, without assuming post-encoding
Source-Monitoring-like decision processes which have explicitly been ruled out by prior research.
Alternate accounts to consider are source errors resulting by chance from guessing processes or verbal encoding of
largely non-verbalizable action items. However, overall the simulation shows that participants made more source
errors and fewer intrusion errors than would be predicted by chance performance, suggesting that biases beyond
chance are responsible for the observed results.
Lindner, I., Echterhoff, G., Davidson, P. S. R., & Brand, M. (2010). Observation inflation. Your actions become mine. Psychological Science, 21(9), 1291–9.
Perfect, T.J., Berry, C., Lange, N., Levitt, C. & Dennis, I. (submitted). I told you so: during recall people give away more answers than they plagiarise.
Nick.Lange@plymouth.ac.uk