This study examined substance use and memory in incarcerated offenders’ accounts of past events. One- hundred-fifty male violent offenders reported memories for perpetrated violence, a positive event, and a subjectively disturbing event. Interviews were transcribed and trained coders counted the number of details in each memory report. Participants also rated their own memories for vividness, detail, and overall quality. Most participants were under the influence during their recalled acts of perpetrated violence. Surprisingly, participants under the influence reported more details than those who had not used any substances. These findings have important implications for how offender testimony is considered.

1. Encoding violence under the
influence: The impact of alcohol and
drug use on perpetrator’s memories
for violent crimes
Marguerite Ternes1, Barry S. Cooper2, & Dorothee Griesel3
1Saint Mary’s University
2University of British Columbia, Private Practice
3Gesellschaft für Wissenschaftliche Gerichts- und Rechtspsychologie

2. Substance Use & Crime
• Alcohol/drug-related crimes are
exceptionally common.
 Often the offender, victim, or an eyewitness is
intoxicated at the time of the crime.

3. Substance Use & Memory
• Substance use impairs memory, in general.
• Relationship between substance use and
eyewitness memory is more complex.

4. The Current Study
• Aimed to explore relationship between substance
use and memory for:
 Perpetrated violent events
 Subjectively disturbing events
 Positive events
• We expected substance use at time of event to
lead to poorer memory.

5. Method
• Participants
 150 male incarcerated violent offenders
 Mean age was 34.93 years (range 19 - 77 years)
 65% Caucasian, 17% Aboriginal, & 18% were mixture of ethnic
backgrounds
 Avg of 11.25 yrs of education (range 4.5 – 18 years)
 Avg of 6.23 yrs of incarceration (range .08 - 27 years)
 58% interviewed at Mountain Institution and 42% interviewed at
Kent Institution.
 Recruited through signs throughout institution or by word of
mouth.
 Interviews took place in private office in psychology department or
in the participants’ living units.
 Interviews took ~5 hours to complete.

6. Method
• Memories
 Each participant asked to provide memory for:
 Positive event
 Subjectively disturbing event
 Instrumentally violent event
 Reactively violent event
 Violent event for which he had poor memory
• Interview included questions regarding substance use and
intoxication during each event.
• Quality of memory assessed via Memory Characteristics
Questionnaire (Johnson et al., 1988).

7. Results/Discussion:
Alcohol Use, Drug Use, & Intoxication
0
10
20
30
40
50
60
70
80
90
100
Positive Subjectively
Disturbing
Instrumental
Violence
Reactive
Violence
Lack of Memory
for Violence
Percentage Under the Influence

8. Results/Discussion:
Alcohol Use, Drug Use, & Intoxication
0
10
20
30
40
50
60
70
80
90
Positive Subjectively
Disturbing
Instrumental
Violence
Reactive
Violence
Lack of Memory
for Violence
Proportion Intoxicated

9. Results/Discussion:
Alcohol Use, Drug Use, & Intoxication
0
10
20
30
40
50
60
70
80
90
Positive Subjectively
Disturbing
Instrumental Violence Reactive Violence Lack of Memory for
Violence
Alcohol Drugs Alcohol & Drugs

10. Results/Discussion: Quality of
Memory
0
1
2
3
4
5
6
7
Under Influence No Substances
Positive Subjectively
Disturbing
Instrumental
Violence
Reactive
Violence
Lack of Memory
For Violence
*

11. Results/Discussion: Quality of
Memory
0
1
2
3
4
5
6
7
Intoxicated Not Intoxicated
Positive Subjectively
Disturbing
Instrumental
Violence
Reactive
Violence
Lack of Memory
For Violence
* *

12. Results/Discussion: Quality of
Memory
0
50
100
150
200
250
300
350
Positive Subjectively
Disturbing
Instrumental Violence Reactive Violence Lack of Memory for
Violence
Under Influence No Substances
*
*
*
*

13. Results/Discussion: Quality of
Memory
0
50
100
150
200
250
300
350
Positive Subjectively
Disturbing
Instrumental Violence Reactive Violence Lack of Memory for
Violence
Intoxicated Not Intoxicated
*

14. Conclusion
• Substance use at the time of crime was common.
• Offenders who were under the influence at the
time of their crime can remember the event with
much detail.
• Intoxication does not necessarily cause amnesia!
• Future plans: Look at other variables

15. Thank you!
Contact Information:
Meg Ternes
Saint Mary’s University
Halifax, NS
Meg.Ternes@smu.ca