Prospective Memory and Working Memory in Adults with Autism Spectrum Disorder

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Prospecve Memory and Working Memory in Adults with
Ausm Spectrum Disorder
Catherine Grainger1, David Williams1, Sophie Lind1 & Chris Jarrold2
1Department of Psychology, Durham University, 2Department of Psychology, Bristol University
Introducon
 “Event“Event-
-basedbased” ” prospecve memory (PM) involves remembering to carry out
an intenon upon the occurrence of a specied event (e.g., remove a pan
from the stove when the mer goes o).
 ““TimeTime-
-basedbased” ” PM involves remembering to execute an intenon at a parcu-
lar me (e.g., to remove the pan from the stove in 10 minutes).
 Ausm spectrum disorder (ASD) Ausm spectrum disorder (ASD) is a developmental disorder that is
characterised by a parcular prole of strengths and weaknesses in
memory and cognion, although very few studies have explored PM.
 Williams et al., under review found impaired me-based, but unimpaired
event-based, PM in children with ASD. However, parcipants may have been
compensang for underlying decits in event-based PM
 Most neurotypical adults spontaneously recall their intenon upon the occur-
rence of the event (Ward et al., 2005), but individuals with ASD may succeed
on event-based PM tasks by rehearsing their intenon throughout. Under
these condions performance would depend on Working MemoryWorking Memory (WM),
the ability to hold informaon in mind during potenally distracng acvity.
 In this study, adults with ASD and typically developing (TD) comparison adults
completed novel tests of event-based and me-based PM, as well as tests of
verbal and visual WM. Parcipants also self-reported the extent to which
they connuously searched for targets during the event-based PM task.
Predicons
1. Time-based, but not event-based PM will be impaired in individuals with
ASD.
2. Verbal WM will be intact in individuals with ASD
3. Event-based PM performance will be signicantly correlated with verbal
WM (but not visual WM ) in individuals with ASD.
4. Individuals with ASD will self-report searching for targets in the event-
based PM more than typically developing individuals.
Results
Correlaonal analysis
 Event-based failures * Verbal WM: : ASD:ASD: r r = .58, = .58, pp= .02; = .02; TD: r = .30, p= .27
 Event-based failures * Visual WM: ASD: r = .19, p= .50; TD: r = .26, p= .34
Method
 Search Queson: Parcipants were asked to rate on a scale of 1-10 the ex-
tent to which they acvely searched for the event-based target throughout
the task (10 = searched the whole me; 1 = spontaneous retrieval of inten-
on, having not thought about it during the task).
 Visual Storage task: Squares were presented to parcipants in dierent
locaons, in sequences of three to eight squares. Parcipants were asked
to recall the locaon the squares, in the order they saw them.
 Verbal Storage task: Numbers were presented to parcipants, in sequenc-
es of three to eight. Parcipants were asked to recall the numbers they
saw, in the order they saw them in.
Discussion
 Predicted decits in me-based PM were found in individuals with ASD.
No group dierences in event-based task performance were found.
 Verbal WM was not impaired in individuals with ASD, whereas visual WM
was.
 In individuals with ASD event-based PM performance was signicantly as-
sociated with verbal WM (not visual WM), whereas verbal WM was not
signicantly associated with performance in controls.
 More than half the parcipants with ASD reported acvely searching for
the event-based targets, compared to just over a quarter of the TD parci-
pants
 These results suggest that individuals with ASD use atypical compensatory
strategies to perform well on event-based tasks despite limited underlying
competence.
Future research uture research could examine whether:
a) Suppressing verbal WM would cause greater impairments in PM perfor-
mance in individuals with ASD, compared to matched controls.
b) Improving WM ability (e.g. Holmes et al.,2009 ) in individuals with ASD
could improve ability in other types of memory.
+
Smuli
Smuli
Smuli
Smuli
Smuli
Individual smuli presented
for 1000ms each
List of smuli appears for 5000ms, during
which parcipants made a correct/incorrect
response.
Smuli
500ms xaon cross
Smuli
List of 7 Words
Figure 1: Outline of the ongoing task used in the
PM tasks.
Time-based Task:
The prospecve memory in-
strucon was to press a
buon aer two minutes of
the task .
Event-based Task:
The prospecve memory in-
strucon was to press a
buon every me they saw a
musical instrument in the list.
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
Event-Based Task
Time-Based Task
Prospective Memory Task
TD
ASD
: p= .03
Figure 2: Number of incorrect me-based and event
-based PM trials, for individuals with ASD and TD
individuals.
0
2
4
6
8
10
12
14
16
18
Verbal Storage
Visual Storage
Working Memory Task
TD
ASD
: p=.04
Figure 3: Visual and Verbal WM performance, for individuals with ASD and
TD individuals.
Mean number of
incorrect trials
Number of trials
correct
Table 1: Parcipant Characteriscs
Group
ASD (n = 15 ) TD (n = 15) t p Cohen’s d
Age 31 (9) 34 (15) -0.72 .47 -0.26
VIQ 111 (15) 109 (9) 0.39 .70 0.14
PIQ 114(14) 115 (12) -0.08 .93 -0.03
AQ 35 (9) 13 (6) 7.51 <.001 0.81
Table 2: Mean response to the
search queson, in individuals with
ASD and TD individuals.
Group
ASD TD Stasc p
Mean
Score
5.3
(3.2)
4.4
(2.8)
t=
0.79
.43
Proporon
of group
with a
score >5
.53
.27
χ2=
2.22
.07
References
Holmes, J. Gathercole, S. & Dunning, D. (2009). Adapve training leads to sustained enhancement of poor working memory in children.
Developmental Science, 12, 9-15.
Ward, H., Shum, D., McKinlay, L., Baker-Tweney, S., & Wallace, G.(2005). Development of prospecve memory: tasks based on the prefron-
tal-lobe model. Child Neuropsychology, 11, 527-49.
Williams, D., Boucher, J. & Jarrold, C. (under review). Time-based and event-based prospecve memory in children with ausm spectrum
disorder.