Episodic (Contextuai) Memory

3.6.1 Introduction

The previous sections have shown that the Autistic groups had an increased deficit in memory tasks that have greater reliance on episodic (or contextual) memory. In this section, further evidence is provided for impaired episodic memory in these children.

A number o f studies have shown that individuals with Autism have difficulty with contextual memory. Boucher and colleagues showed that children with Autism (CA 13:2, VMA 7:2, NVMA 10:6) were significantly less able than controls to recall the context and order of recent activities in which they had participated. The same children, however, performed at levels similar to controls when asked questions about the events of the testing, which included contextual cues [Boucher 1981; Boucher and Lewis 1989]. In the more extensive of these two studies, children participated in four experiments over a period o f 6- 12 months. At least 1 month after completing the last experiment, the child was then asked to recall the activities previously completed with the experimenter [Boucher and Lewis

1989].

Other studies have shown impaired event memory in individuals with Autism. Jarrold and Russell asked the children in their study how they knew what was in a box (were they told or did they see) and who had placed a card into a grid (either the child, the experimenter or a doll manipulated by the experimenter or child). The children with Autism were severely impaired on this task in comparison to controls [Jarrold and Russell 1996]. Millward et al.

further showed that children with Autism (CA 13:1, VMA 6:3) had more difficulties recalling events that they had personally experienced than events that they saw another child experience [Millward et al. 2000]. This last finding may be argued to be more a reflection of a lack of insight into self, rather than a memory deficit per se. However, the study has an important confound. Children’s memories for events are enhanced by

more likely than children with Autism to provide a spontaneous narration of the events happening to them. Thus the children with Autism might have recalled events occurring to other children better due to the benefits of narration.

In this section, two measures of episodic memory are used, the Rivermead Behavioural Memory Test and the Sunderland Parental Memory Questionnaire.

3.6.2 Methods

The Rivermead Behavioural Memory Test [Wilson et a l 1991] was administered according to the manual, and age norms were used to calculate standardised scores. The test consists of a series of subtests, as detailed below. Raw scores from each subtest were converted into scaled scores, where 2 indicated normal performance, 1 indicated mild impairment and 0 indicated severe impairment. Scaled scores (for children aged 6+) were provided by the manual.

Remembering a name The child was shown a photographic portrait and told the first and second name of the person in the photograph. He was asked to repeat their name and then remember it. After a filled delay o f over 20 minutes, the child was asked to recall the name. Partial credit was given for recall o f the name following the prompt o f the initial letter.

Belonging The child was asked for a belonging (such as a handkerchief, watch, etc.) and told that the examiner was going to hide the object. He was asked to remember where it was hidden and to ask for it when the examiner said that the test was over. After a filled delay o f over 20 minutes, the child was told that the test was over. Credit was given for remembering the item and where it was hidden. Partial credit was given for remembering following a prompt.

Remembering an appointment The child was shown an alarm clock. The alarm was set for 20 minutes and the child was told to ask the examiner when the alarm rings when he would next be seeing the examiner. A practice was given. If, when the alarm rang, the child did not respond, he was prompted. Partial credit was given for remembering that he was supposed to do something.

Pictures Ten black and white line drawings were shown to the child, one a time, each for 5 seconds. After a brief, filled delay, the child was asked to pick out the drawings seen earlier fi*om a set of 20 drawings.

Story The child was read a short story and asked to recall it

immediately exactly as read. After a delay the child was asked to recall the story again.

Faces Five faces were presented to the child, one at a time. The

child was asked to remember them. After a brief delay, the child was shown 10 faces and asked to indicate which ones had been seen earlier.

Remembering a route The examiner traced a short route around the testing room. The route involved five locations. As the examiner completed the route, a verbal commentary was given, naming all the locations. The examiner took a message, and left it at stage 4 of the route. The child was required to follow the route immediately and after a delay of approximately 20 minutes.

Remembering to deliver a message The child was also scored on remembering to take the message and leaving it at the appropriate location. The child was prompted to take the message if he did not spontaneously pick it up. This was scored on both immediate and delayed recall of the route.

Orientation questions The child was asked 11 questions to determine orientation to date, time, place, awareness o f age, birthdates, etc.

The Sunderland Parental Memory Questionnaire was used to assess aspects of real life everyday memory that are otherwise difficult to measure through standardised tests or through experimental measures [Sunderland et a l 1983]. Parents rated each of 28 items from A (has not occurred in the last 3 months) to I (occurs at least once a day). Scores of 1-9 were assigned to ratings A to I and these were summed for each child.

3.6.3 Results

Results from the Rivermead Behavioural Memory test (Figure 3:10) show that there was a significant difference between the three groups, with both the High and Low groups

comparisons: CvH t = 4, df = 17.8, p < 0.001; HvL t = 2, df = 17.7, p = 0.1). These differences were not accounted for by VIQ (ANCOVA F(2, 40) = 7, p = 0.003) nor by sustained attention (ANCOVA F(2, 39) = 11, p < 0.001). This significant difference between the groups was also found when the analysis was restricted to just the boys’ data. The pattern o f performance on the recognition of faces and pictures and story recall was similar to that reported for similar subtests in previous sections. The pattern of performance on the subtests can be seen in Figure 3:11.

Figure 3:10 Rivermead Behavioural Memory Test (Mean ± SEM)

22-1 2 0- Î5-18- N 16- ra 14- £ .12- 2 1 0- 8- o in 6- 4- 2- 0

Control High Low

Figure 3:11 Rivermead Behavioural Memory Subtests (Name, Belonging, Appointment, Picture recognition, Story immediate and delayed. Face recognition. Route bnmediate and delay, message and orientation) (Mean ± SEM)

8 B 0> o H o CO

1

I

JIJ

Name Belong Appt Pic Stor I Stor D Faces Rte

1 = 1 Control E = High Low

The results from the Sunderland Parental questionnaire confirm the results of the RBMT (see Figure 3:12) . There was a significant difference between the three groups, with both Autistic groups scoring significantly higher (indicating greater impairment) than the Control group (ANOVA: F(2, 38) = 12, p < 0.001; Planned comparisons CvH: t = -4, d f = 13.8, p = 0.002; HvL: t = -0.7, df = 22.9, p = 0.5). This difference was not accounted for by VIQ (ANCOVA: F(2, 37) = 7, p = 0.002).

Figure 3:12 The Sunderland Parental Memory Questionnaire (Mean ± SEM)

140n o 1 2 0- 100- 80-

8

Control High Low

3.6.4 Discussion

The results from two well-established measures o f episodic memory demonstrate that both Autistic groups are impaired on this aspect o f memory. The Rivermead scores highlight prospective memory (i.e. memory that allows the realisation of delayed intentions) as particularly impaired.

No previous studies have investigated episodic memory in Autism using comparable paradigms. However these findings are consistent with studies investigating memory for events (e.g. Boucher 1981; Boucher and Lewis 1989; Jarrold and Russell 1996; Millward et a l 2000) (see Section 3.6.1). Gardiner and colleagues found a deficit in episodic memory in adults with Autism using a remember-know paradigm [Bowler et a l 2000].

information is presented. For example Hermelin and O’Connor found that, compared to controls matched on digit span, children with Autism (CA 11:6, VMA 4:9) did not show the same enhanced memory for meaningful word phrases relative to unrelated words [Hermelin and O'Connor 1970]. A number of studies have suggested that individuals with Autism are comparatively more impaired at recall of related word lists compared to unrelated word lists (see Tager-Flusberg 1991a; Bowler et a l 1997 but see Beversdorf et a l 1998).

Echoing the animal work, as well as a failure to utilise relevant contextual information, individuals with Autism also show over-reliance on irrelevant contextual information. For example, children with Autism often fail to recognise familiar objects or people in a new context [Waterhouse 1987] and show disproportionate distress at changes in routine.