Influence of age on the effects of lying on memory

Abstract

False memories are elicited from exposure to misleading information. It is possible that self-provided misinformation, or lying, has similar effects. We hypothesized that lying impairs memory for younger adults, as increased cognitive control, necessary to inhibit a truthful response, comes at the expense of retaining veridical information in memory. Because older adults show deficits in cognitive control, we hypothesized their memory is unaffected by lying. In the present study, participants made truthful and deceptive responses on a computer while EEG data were recorded. We investigated medial frontal negativity (MFN), an ERP component associated with deception and cognitive control, which may be differentially generated across age groups due to differences in cognitive control. Unexpectedly, results revealed that older adults showed reduced accurate memory for items to which they previously lied compared to younger adults. There were no age differences in correct memory for truth items. We did not find the expected MFN effect, however results revealed long-lasting negative slow waves (NSW) to lie items across age in the pre-response period and following the response cue, suggesting the role of working memory processes in deception. These findings demonstrate that lying is another source of misinformation and influences memory differently across the lifespan.

Keywords: Aging; Cognitive control; Lying; Memory; Working memory.

Figure 1.

Design of Questionnaire 1 with example stimuli. Participants completed the 102-item questionnaire on the computer where there were asked whether they completed certain actions in the course of the day yesterday. For some of the questions, participants were instructed to lie and for other questions, participants were instructed to tell the truth (randomized). Questions required a “yes” or “no” response via button press.

Figure 2.

Design of Questionnaire 2 with example stimuli. Participants completed the 102-item questionnaire on the computer where they were asked whether they completed certain actions in the course of the day yesterday. Participants were instructed to answer truthfully to all questions. Questions required a “yes” or “no” response via button press.

Figure 3.

Correct memory performance by instructions and age. The graph depicts the proportion of correctly remembered items, separated by age group, based on whether participants were instructed to tell the truth or lie. Younger and older adults did not differ in correct memory for truth items. However, older adults had reduced correct memory for items to which they previously lied compared to younger adults. Correct memory was greater for truth items than lie items.

Figure 4.

Response time for correctly remembered items by instructions and age. The graph depicts the average response time, separated by age group, for items to which participants told the truth and lied. Younger adults had a faster response time than older adults for both truth items and lie items.

Figure 5.

ERP results using mass univariate analysis to look at the four electrodes of interest. The raster plots presented here show a graphic representation of results, where the warmer the colors, the more significant a given time point in the electrode is. Within the 0–150 ms time window post response, response to truth items was more negative than response to lie items at FC1, FC2, and Cz towards the end of the selected time window (~150 ms). There were no differences across age.

Figure 6.

Activity at each of the four electrodes of interest. Activity is shown at FC1, FC2, Fz, and Cz. The black (response to truth item) and red (response to lie item) lines depict activity for younger adults. The blue (response to truth item) and green (response to lie item) lines depict activity for older adults. ERP data is time-locked to the response (e.g., 0 point on the x-axis) and epoched from 200 ms prior to response to 800 ms after a response is made. The y-axis reflects magnitude in μV. Analysis was conducted within the 0–150 ms time window post response. Results show a greater negative amplitude for truth responses than lie responses, for both younger and older adults.

Figure 7.

ERP waveforms that were not baseline corrected. Given the differences across age groups, data were re-processed without baseline correcting to check whether baseline activity was driving the effects or masking other effects. The graphs are from electrode Fz (left), which was representative of the other electrodes. A black line depicts response to truth items. A red line depicts response to lie items. ERP data is time-locked to the response (e.g., 0 point on the x-axis) and epoched from 1000 ms prior to the response to 1000 ms after the response. The y-axis reflects magnitude in μV. For all panels, younger adults are shown on the top, older adults are shown on the bottom. Older adults had greater negativity than younger adults. Visually inspecting the waveforms revealed that response to lie items exhibited a greater negativity than response to truth items, albeit this difference did not reach significance. The topographic maps (right) depict the distribution of effects across the scalp, where the warmer the colors, the more significant the effect in a given location is.

Figure 8.

ERP data with long epoch. Data were re-processed with a longer epoch from −200 to 7000 ms to better characterize the landscape against which effects emerged. ERP data is time-locked to the item/instruction cue (e.g., 0 point on the x-axis). The y-axis depicts magnitude in μV. A) The graphs are from electrode AF4 (left), which was representative of the other electrodes. A black line depicts truth items. A red line depicts lie items. For all panels, younger adults are shown on the top, older adults are shown on the bottom. Both younger and older adults show greater frontal negativity for lie items than truth items around 4000 ms. The topographic maps (right) depict the distribution of effects across the scalp during this time window, where the warmer the colors, the more significant the effect is in a given location. B) Differences in instruction emerged after the onset of the response cue, where lie items show greater frontal negativity than truth items.

Figure 9.

Regression results showing predictive effects of frontal negativity on correct memory performance. To assess whether frontal negativity predicts correct memory performance, mean values from lie minus truth and memory performance were included in a linear regression. Frontal negativity was treated as a continuous variable with age as a categorical predictor, controlling for social desirability. Two separate regressions, one for correct memory for truth items and one for correct memory for lie items, were conducted. The graphs represent the two-way interaction depicting the relationship between correct memory performance (y axis) and frontal negativity (x axis) for each instruction type, moderated by age group. Neither age nor frontal negativity predicted correct memory for truth items. Age predicted correct memory for lie items, as younger adults had better correct memory for lie items relative to older adults.