Picture and word false memory in autism spectrum disorder, Megan Borlase
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Picture and word false memory in autism spectrum disorder, Megan Borlase
- 1. Picture and Word False Memory in Autism Spectrum Disorder: A Developmental Perspective Megan Borlase & Ewald Neumann University of Canterbury
- 2. AUTISM SPECTRUM DISORDER (ASD) Organization Empathy Theory of Mind Co-ordination Inhibitory Control LANGUAGE BEHAVIOUR SOCIAL AUTISM Intellectual Memory Perception Executive functions Central Coherence Attention
- 10. WORD STIMULI CRITICAL LURES STUDIED WORDS NOVEL WORDS (Recognition Task only) E.g., Hammer E.g., Nail, Builder, Saw, Wrench, Screwdriver, Axe, Tape measure, Screw E. g ., Throne, Queen Crown, Castle
- 11. PICTURE STIMULI CRITICAL LURES STUDIED WORDS NOVEL WORDS (recognition task only) E.g., E.g., E.g.,
- 15. Differences in confidence ratings of word false critical lure recognition between ASD and control children, adolescents and adults (n.s.)
- 22. Improvement in the correct rejection of CLs and recognition of studied words as a result of working collaboratively for ASD and control groups p<0.05 p<0.05 n.s. n.s.
Editor's Notes
- “ Imagine being snatched up by a helicopter that whisks you away and dumps you in a bazaar in Morocco. You’re given no instructions on what to do and how to live; you don’t understand the customs or know the language.” That ladies and gentlemen is how life is everyday for someone with Autism Spectrum Disorder or ASD.
- Autism Spectrum Disorder, an umbrella term for Autism and Asperger’s Disorder, is a developmental disorder with an international incidence rate of approximately 1 in 100. This group of disorders varies greatly between diagnosed individuals but is primarily characterised by social, behavioural and language deficits. These deficits vary in severity and can be accompanied by any number of cognitive or motor deficits – for example executive function, attention, inhibitory control, central coherence and memory deficits. My thesis focuses on whether these deficits affect false memory from childhood through to adulthood.
- Well first of all what are false memories? Basically any memory that we have of an event that we did not actually experience is deemed a false memory. Instances where false memories hold particular relevance outside the laboratory setting are eyewitness testimonies and cases of repressed memory. Take for example the case of Beth Rutherford who, in 1992, undertook therapy with a church clergyman who helped her uncover memories of her clergyman father raping her between the age of 7 and 14, on occasion with her mother holding her down. Furthermore she believed that her father had impregnated her twice forcing her to abort both pregnancies with a coat hanger. As a result of this her father had to resign his post; despite the fact that a medical examination later found that Beth at age 22 was still a virgin and had never been pregnant. As you can see false memories can have a huge impact on someone’s life and be held with as much conviction as a true memory making the two very hard to discern. There are several ways that false memories can be tested in a laboratory setting using suggestive stories, pictures and film clips or through tasks such as the DRM task which uses semantically associated word lists to create false memories.
- Before I go into the DRM in more detail I would like to highlight the effectiveness of these suggestive methods by looking at a study conducted by Braun and colleagues. They carried out a study using false advertisements for Disneyland such as this one featuring a picture of Bugs Bunny who as you may know is a Warner Bros character. This one reads – “take a look back into your childhood...try to recall the first time you visited a Disney theme park…bring that image to mind…see Cinderella's castle glisten in the bright sunlight…smell the fried foods…feel the breeze that cooled the sweat you worked up as you ran from ride to ride to fit the most excitement into your day. Recall the pride you felt as you cleared the height requirement indicated by the character’s wooden hand…that allowed you to go on the really cool rides like space mountain. You were in your element…festival food, scary rides and exciting shows. With the song “it’s a small world after all” in your mind you ventured back to your hotel to rest up for another day. Just then you spotted one of the characters, looks like Bugs Bunny! He waved you over. Adrenaline rushed through you and you managed to move your feet in his direction. He shook your hand. The perfect end to a perfect day.” As a result of the posters 16% of people believed that they had met and shaken Bugs Bunny’s hand while they were visiting the theme park. Later studies had 25-35% of participants claiming to have met Bugs at Disneyland.
- A common method of testing false memories because of how easy it is to replicate is the DRM task which was developed by Deese, Roediger and McDermott and uses lists of semantically associated words to measure the occurrence of false memories. It does this through the use of lists of words associated to a critical lure which is not presented during testing e.g. “bed, rest, awake, tired, dream, slumber, snooze, snore” are related to the unpresented critical lure ‘sleep’. So when asked to complete a recall or recognition task of the words presented during testing any critical lures that a participant recollects would constitute a false memory as we know those lures were never presented. In Roediger and McDermott’s 1995 study they found that participants falsely recalled 55% of the critical lures. If recall was followed by a recognition task then the percentage of lures falsely recognised was 72% and if they only completed a recognition task they falsely recognised 53% of the critical lures.
- Numerous studies have built on the foundations of the DRM study looking at false memory in different subsets of the population, for words, pictures, sentences, sections of prose and through different testing methods – free recall, recognition or a combination of the two. Studies looking at false memory in children have found them to have lower critical lure recollections than adults something that may be due to the development of associations in the brain. Research comparing picture to word false memory rates have found lower false memory in picture conditions with the more distinctive or detailed pictures resulting in even lower false memory in DRM tasks. DRM studies looking at false memory in adults with ASD have found conflicting results with some studies stating ASD participants had lower studied item and similar false critical lure recognition than controls with others have shown that ASD participants have lower false and studied item recognition than controls. It has also been suggested that ASD individuals have poorly developed association networks which relates back to the idea of a weak central coherence in this group. It has been found that ASD adults are more confident in their true and false recognitions than controls. Need the reasons.
- We carried out two experiments – the first concentrated on the age differences in individuals’ true and false recognition and the second concentrated the effects working in groups of three has on false recognition in ASD and control participants.
- In experiment one we tested the hypothesis that false critical lure recognition will increase with participant age but will always be similar for ASD and control participants.
- To test this hypothesis we adapted word and picture lists from Carlin et al. who used picture DRM lists with adults with a mental age of 6 and compared them with mental-age and chronological-age matched (adults) controls. The lists employed categorical associations and resulted in the 6 year old controls and intellectually disabled adults having fewer critical lure and studied item recognitions than control adults.
- In our study participants were presented with a list such as “nail, builder, saw, wrench, screwdriver, axe, tape measure and screw” which are expected to elicit the false recognition of the critical lure ‘hammer’.
- The same idea applies to both word and picture lists. Word and picture presentations each included 6 lists presented in succession and taking roughly 4 minutes per presentation.
- Following each presentation participants were given a 60 item recognition task made up of the 6 unpresented critical lures, 5 studied items from each list and 24 unrelated novel words. The researcher would ask participants questions phrased as ‘Did you hear or see…’ for each item and participants would then indicate their confidence in the decision made by circling ‘no’, ‘I don’t think so’, ‘I think so’ or ‘yes’ for each item.
- ASD and control participants showed similar age related trend for both word and picture false critical lure and actual studied item recognition. Studied item recognition increased with age and critical lure recognition was lowest for adults followed by children. As we age our association networks expand and develop which would cause higher critical lure and studied item recognition. However the adults had lower critical lure recognition than the children, possibly because the lists we used are categorical and are child-normed. This is the same trend Carlin et al. found with their lists but does not reflect the usual developmental trend with false memories as they usually increase with age. There were no significant differences between groups for pictures so we have concentrated solely on word data here.
- When we broke down the age differences and looked directly at the differences between ASD and controls we found that ASD participants had higher critical lure recognition than controls. We believe that this indicates a functioning association network in ASD however due to an impairment in inhibitory control their critical lure recognition is higher than controls. Basically, when they heard or saw the items the associated critical lure was automatically brought to mind but they were less able to prevent, or inhibit, it from intruding during the recognition task than controls because of impaired inhibitory control. It is very interesting that these findings differ so greatly from earlier studies and this may again be due to the type of lists we used. It is important to note that there were no significant differences in studied item recognition which suggests that the two groups are closely matched for this type of task.
- ASD participants were more confident in their false critical lure recognitions than controls except in the ASD adults who showed the least certainty in their decisions, within the ASD participants, and lower confidence than age matched controls. Aside from this group confidence increased with age, this is particularly clear with the controls. Confidence ratings for studied items were very similar for ASD and control participants with little difference between age groups.
- The second experiment we conducted looked at the effects of working in a collaborative trio on critical lure and studied item recognition in both ASD and control children and adolescents. This is particularly interesting due to social deficits, in particular, difficulty with social understanding being the hallmark feature of ASD. This deficit means people with ASD have difficulty understanding and appreciating the thoughts and feelings of other people which could make working together in a collaborative trio difficult.
- Early studies of collaboration in neuro-typical adults have found that collaboration improves studied item recognition and the correct rejection of critical lures. It has also been found that the type of decision making used by a collaborative trio can affect the degree to which collaboration can improve memory. Using a majority rule system is beneficial to the correct rejection of critical lures however evidence based discussion is most beneficial to studied item recognition. Just to clarify majority rule means using the response that two of the three participants gave and evidence based discussion is where the groups make decisions based on convincing arguments given by group members such as ‘apple’ was in with the fruits or the ‘dress’ was pink and lacy et cetera. The last thing we have taken away from previous studies is that, when young and old adults were compared, collaboration resulted in more false memories in the older adults than in the young adults, similar to the age effects found in individuals.
- We hypothesized that collaboration would increase total recognition and accuracy, to a greater extent, for participants with ASD than controls and that this benefit would increase with age.
- To test this we used the same stimuli and methods as we used in experiment one except after each presentation the participants would complete the recognition task individually and then as a collaborative trio.
- When we compared studied item and false critical lure recognition between collaborative trios and individuals we found that collaboration resulted in a clear benefit of fewer critical lure and more studied item recognitions. This pattern was averaged across age groups and ASD and control participants.
- Both critical lure and studied item recognition, was higher for the adolescent trios than collaborative children for both ASD and controls. Only the critical lures revealed a significant difference.
- When we broke down the collaboration results further and looked directly at the amount of improvement, or decrease in critical lure recognitions and increase in studied item recognitions, we found some interesting patterns. ASD children showed no improvement in correct critical lure rejection from working collaboratively, and a decrease in studied item recognition. Whereas ASD adolescents and all controls clearly benefitted from collaboration. At this stage we are unsure why collaboration had such a negative effect on autistic children while benefitting the autistic adolescents but if anyone has any ideas please come and see me later as I would appreciate the input. It is interesting to note that the autistic adolescents generally employed the majority rule decision making technique whereas the control adolescents mostly used evidence based discussion. This may be the reason why autistic adolescents showed a greater benefit in the correct rejection of the critical lures and a smaller benefit in studied item recognition than the control adolescents. These observations were not documented, and I cannot recall how collaborative control children made their decisions, but this would be something worth looking into in future studies of the collaboration effect in ASD as these findings, of benefits in autistics adolescents, suggest a possibility for similar benefits in group learning and therapy with this age group.
- In summary ASD participants had similar studied item and higher false critical lure recognition than controls possibly due to impaired inhibitory control. Studied item recognition increased with age as did critical lure recognition in both individuals and collaborative trios. Adults had lower critical lure recognition than younger groups possibly due to the use of categorical lists. ASD participants generally had higher confidence in their false memories than controls, and collaboration was detrimental to ASD children but beneficial to all other groups most likely resulting from the decision making techniques applied.