This thesis investigates source memory for performed and observed actions in recall and recognition tasks. The motor simulation account predicts that motor activation during action observation results in source misattributions of observed actions as self-performed. Alternatively, source judgements at test may be based on the evaluation of source features (source monitoring framework) or memory strength (relative strength account). Experiments 1, 2 and 3 in Chapter 2 test if the motor simulation account explains false memories of self-performance after observation. Interfering with participants’ ability to encode the motor trace during observation does not reduce participants’ propensity to falsely recall observed actions as performed, but increases it. Experiment 4 in Chapter 3 manipulates motor and visual interference at retrieval. Participants’ false recognition of observed actions as performed and performed actions as observed is not significantly affected by motor or visual interference. Experiments 5, 6 and 7 in Chapter 4 test if participants are better able to discriminate performed and observed actions if they generate the idea for the action they perform themselves. Participants’ source discrimination in a recall task improves if they generate the ideas for self-performed actions (Experiment 5 and 6), only if they do not also generate ideas for actions they observe (Experiment 7). Experiment 8 in Chapter 5 manipulates participants’ visual perspective of actions they observe. There is no evidence for a significant effect of visual perspective during observation on subsequent false memories of self-performance in a recognition paradigm. In my thesis I find no substantial support for a motor simulation account. While the results are broadly compatible with the source monitoring framework, model-based analyses show that participants’ performance may be based on items’ overall strength, in line with the relative strength account, rather than evaluation of source features.

Episodic memory is a critical component of human cognition. Episodic memory involves recollection of the contextual details surrounding an event, the capacity for mental time travel of past and future events, and is characterized by the subjective awareness that an event has been personally experienced. It is fundamental to our understanding of this complex memory system to examine how episodic memory emerges during the course of development. The present investigation explored the developmental improvement in episodic memory processing assessing recollection of factual information and the source of this information (i.e., source memory) between early to middle childhood. The electrophysiological (EEG) correlates of fact and source memory processing and measures of executive function were also examined as potential sources of variation in episodic memory. The focus of Study 1 was to examine source memory development in early childhood in a sample of 4- and 6-year-olds. Results revealed that older children were better able to recall both fact and source information. Source memory measures were correlated to early executive ability, namely measures of working memory, inhibitory control and set-shifting. Frontal EEG accounted for unique variation in fact recall but not source recall, whereas temporal EEG did not predict fact or source recall performance. The focus of Study 2 was to examine source memory development in middle childhood in a sample of 6- and 8-year-olds. Older children were better on fact recall, but both ages were comparable on source recall. Frontal EEG uniquely predicted fact recall performance beyond the contribution of age and language. Both frontal and parietal EEG and executive function predicted variation in source recall performance. In contrast, temporal EEG did not uniquely predict fact or source recall performance. Lastly, Study 3 was a longitudinal investigation of source memory between early and middle childhood. Although age-related increases in performance were evident, Time 1 and Time 2 source memory measures were not correlated. This investigation contributes to our understanding of the developmental changes in source memory processing between early and middle childhood, and identifies that patterns of frontal and parietal brain activity and executive function skills contribute to early episodic memory formation. / Ph. D.

Consider a common social interaction: Two people must each attend to and remember the other person’s behaviour while also keeping track of their own responses. Knowledge of what one said to whom is important for subsequent interactions so that information is not repeated to the same person. Remembering what one said to others is also important in the workplace where supervisors need to remember to whom they have told specific information so that they can later assess assignment progress from the relevant employee. The processes involved in remembering the destination of information will be referred to as “destination memory” in this dissertation. Although there has been extensive research regarding the processes involved in remembering the source of information, or “source memory,” there has been little to no research on destination memory. In a series of four experiments, this dissertation delineates the core features of destination memory. In Experiment 1, a paradigm was developed to assess destination memory in the laboratory. This experiment also corroborated complaints of destination memory failures: Adults have very poor destination memory when compared to memory for the information they tell or the person to whom they tell the information. Destination memory fundamentally differs from source memory in terms of how information is transferred—“input” in the case of source memory and “output” in the case of destination memory. Attention is directed at the processes involved in transmitting information in the case of destination memory which leaves fewer attention resources for associating the information with the person one is telling it to. Therefore, it would be anticipated that destination memory would be worse than source memory. Experiment 2 directly contrasted destination memory and source memory and confirmed that destination memory accuracy was indeed substantially lower than source memory accuracy. Because in the case of a destination event information is self-produced, attention is focused on oneself. Experiment 3 assessed whether self-focus reduces the association between the outputted information and the person that one is telling it to. When self-focus increased, so too did destination memory errors because fewer attentional resources were available to integrate the person-information pairing. This led to the prediction that, in the reverse situation where attentional resources are directed to the person-information pairing at encoding, then destination memory should improve. Experiment 4 confirmed this prediction: Destination memory was enhanced when people’s attention was shifted from themselves to the person-information pairing. This thesis has undertaken to examine a surprisingly neglected component of normal remembering—remembering who one told something to. To study this “destination memory,” a new paradigm is introduced. Across four experiments, destination memory is seen to be quite fallible, more so than source memory. An account is offered in terms of destination memory being undermined by the self-focus that it generates. This view is reinforced by two experiments that show that increasing self-focus reduces destination memory whereas increasing environment-focus improves destination memory. Like source memory, destination memory is a key component of episodic memory, the record of our personal past.

Consider a common social interaction: Two people must each attend to and remember the other person’s behaviour while also keeping track of their own responses. Knowledge of what one said to whom is important for subsequent interactions so that information is not repeated to the same person. Remembering what one said to others is also important in the workplace where supervisors need to remember to whom they have told specific information so that they can later assess assignment progress from the relevant employee. The processes involved in remembering the destination of information will be referred to as “destination memory” in this dissertation. Although there has been extensive research regarding the processes involved in remembering the source of information, or “source memory,” there has been little to no research on destination memory. In a series of four experiments, this dissertation delineates the core features of destination memory. In Experiment 1, a paradigm was developed to assess destination memory in the laboratory. This experiment also corroborated complaints of destination memory failures: Adults have very poor destination memory when compared to memory for the information they tell or the person to whom they tell the information. Destination memory fundamentally differs from source memory in terms of how information is transferred—“input” in the case of source memory and “output” in the case of destination memory. Attention is directed at the processes involved in transmitting information in the case of destination memory which leaves fewer attention resources for associating the information with the person one is telling it to. Therefore, it would be anticipated that destination memory would be worse than source memory. Experiment 2 directly contrasted destination memory and source memory and confirmed that destination memory accuracy was indeed substantially lower than source memory accuracy. Because in the case of a destination event information is self-produced, attention is focused on oneself. Experiment 3 assessed whether self-focus reduces the association between the outputted information and the person that one is telling it to. When self-focus increased, so too did destination memory errors because fewer attentional resources were available to integrate the person-information pairing. This led to the prediction that, in the reverse situation where attentional resources are directed to the person-information pairing at encoding, then destination memory should improve. Experiment 4 confirmed this prediction: Destination memory was enhanced when people’s attention was shifted from themselves to the person-information pairing. This thesis has undertaken to examine a surprisingly neglected component of normal remembering—remembering who one told something to. To study this “destination memory,” a new paradigm is introduced. Across four experiments, destination memory is seen to be quite fallible, more so than source memory. An account is offered in terms of destination memory being undermined by the self-focus that it generates. This view is reinforced by two experiments that show that increasing self-focus reduces destination memory whereas increasing environment-focus improves destination memory. Like source memory, destination memory is a key component of episodic memory, the record of our personal past.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by dopamine dysregulation in several regions of the brain, including the striatum. Because of the intimate connections between the striatum and the frontal lobes, individuals with PD often demonstrate impairments on those tasks relying on the prefrontal cortex (e.g. tests of executive functioning). Source memory, or memory for context, is believed to rely on the prefrontal cortex and has been previously associated with executive functioning performance, although it has received little attention in the PD literature. Executive functioning and source memory were measured in a group of non-demented PD patients and healthy control participants. Within the PD group, an anti-Parkinson's medication withdrawal manipulation was used to examine whether source memory was affected by phasic changes in dopamine levels. Compared to healthy control participants, PD patients were impaired in source memory (both on and off medication) and on two composite measures of executive functioning. Within the PD group, medication administration improved motor performance but did not have a significant effect on source memory, suggesting that source memory may not rely on the dopamine system.

Source memory is defined as memory for not only the core aspect of some event, but additional contextual detail about that core aspect, or item. Source memory tasks are marked by their engagement of prefrontal cortex in addition to the brain circuits required by other episodic memory tasks. The dissertation examines the relationships among source memory accuracy, concurrent brain activity, and general cognitive principles derived from the study of episodic memory more generally. Electrical measures of brain activity (event-related potentials, ERPs) were recorded while manipulating factors hypothesized to improve or worsen source memory accuracy.The first experiment manipulated the task assigned during the encoding phase and its match to the retrieval demands of remembering objects (depicted in drawings) and their colors. As predicted by the principle of transfer-appropriate processing, source accuracy was higher when the encoding task fostered integration of the item (object) and source (color) attributes. Prefrontal activity during the retrieval phase was greatly reduced when retrieval could benefit from transfer-appropriate processing.In associative memory tasks, poor memory performance is observed when the to-be-retained stimuli share elements with other studied stimuli, as in a variety of interference paradigms. The second experiment thus examined the impact of feature overlap on source recognition by varying the quantitative mapping between the shape and color of an object depicted in a drawing. The results showed two frontal processes supporting source retrieval: an early differentiation between stimuli identical to those encoded and those that switch colors from study to test, and a later effect reflecting prolonged memory search that was truncated by reinstating unique object-color pairings at test.The final experiment compared conjunctions of "intra-item" versus "extra-item" features, by placing the features within a single visual object or distributing them across two visual objects. Source accuracy was worse when shape and color were spatially separated, but prefrontal activity did not vary. The insensitivity of prefrontal ERPs to this perceptual manipulation of difficulty stands in contrast to their sensitivity to encoding task. Individual variability in parietal ERPs was strongly correlated with source accuracy, and likely reflects a contribution of visual working memory to long-term memory.

This thesis investigates two source memory errors: observation inflation, where observed actions are misremembered as being performed; and self-action inflation in which self-performed actions are misremembered as having been performed by somebody else. It has been proposed that these inflations occur because of overlapping brain activity during observation and performance. This has been attributed to mirror neurone activity. To test this, observation and self-action inflations are investigated for different types of actions (meaningful, meaningless and communicative) known to evoke different mirror neurone activity. Different age groups (young adult, and elderly) were studied as were the effects of relative ethnicity between observer and performer. The Remember-Know-Guess paradigm was used. This showed that people make inflations with high qualitative details and confidence. As anticipated, elderly participants made significantly more observation inflations than young adults. Across both age groups, significantly more inflations occurred for communicative and meaningful actions than for meaningless actions supporting the idea that mirror neurones may be involved in formation of inflations. However when the effects of relative ethnicity were included in the paradigm it was found that significantly more observation inflations were formed after observing different ethnicity actors. It has been hypothesised that if mirror neurone involvement is involved in observation inflations then the highest number of inflations are expected for the same ethnicity condition because of the overlap between participant and performer. This thesis therefore suggests a less simplistic explanation of the underlying mechanisms responsible for these types of memory error.

abstract: Current theoretical debate, crossing the bounds of memory theory and mental imagery, surrounds the role of eye movements in successful encoding and retrieval. Although the eyes have been shown to revisit previously-viewed locations during retrieval, the functional role of these saccades is not known. Understanding the potential role of eye movements may help address classic questions in recognition memory. Specifically, are episodic traces rich and detailed, characterized by a single strength-driven recognition process, or are they better described by two separate processes, one for vague information and one for the retrieval of detail? Three experiments are reported, in which participants encoded audio-visual information while completing controlled patterns of eye movements. By presenting information in four sources (i.e., voices), assessments of specific and partial source memory were measured at retrieval. Across experiments, participants' eye movements at test were manipulated. Experiment 1 allowed free viewing, Experiment 2 required externally-cued fixations to previously-relevant (or irrelevant) screen locations, and Experiment 3 required externally-cued new or familiar oculomotor patterns to multiple screen locations in succession. Although eye movements were spontaneously reinstated when gaze was unconstrained during retrieval (Experiment 1), externally-cueing participants to re-engage in fixations or oculomotor patterns from encoding (Experiments 2 and 3) did not enhance retrieval. Across all experiments, participants' memories were well-described by signal-detection models of memory. Source retrieval was characterized by a continuous process, with evidence that source retrieval occurred following item memory failures, and additional evidence that participants partially recollected source, in the absence of specific item retrieval. Pupillometry provided an unbiased metric by which to compute receiver operating characteristic (ROC) curves, which were consistently curvilinear (but linear in z-space), supporting signal-detection predictions over those from dual-process theories. Implications for theoretical views of memory representations are discussed. / Dissertation/Thesis / Ph.D. Psychology 2012

The purpose of this project was to compare the Attention to Memory (AtoM) and the Episodic Buffer (EB) Models. The AtoM model proposes that the ventral parietal cortex (VPC) and dorsal parietal cortex (DPC) are responsive to bottom-up and top- down attention to memory, respectively, (Cabeza, 2008; Cabeza et al., 2008; Ciaramelli et al., 2008). The EB model, on the other hand, proposes that the VPC is involved in the episodic buffer component of Baddeley's working memory model (Vilberg & Rugg, 2008). Using objective (source) and subjective (Remember/Know) retrieval tasks, specific patterns of PPC activity were posited based on the propositions of the AtoM model. These expectations included greater VPC activity for Remember and False Alarms compared to Correct Rejections and Subjective Know, greater DPC activity for Know and Objective Remember compared to Subjective Remember and correct rejections, and no difference in VPC activity for remembering both font and color compared to remembering only one contextual detail. During encoding participants saw words in one of two colors, red or yellow, and in one of two fonts, curvy or straight, and were required to indicate the color the word was presented in. Following each encoding scan participants performed either an Objective or Subjective retrieval task. During Objective retrieval task, participants performed a forced-choice source memory test choosing the word with the correct fontand color or the "new" option. During Subjective retrieval participants were presented with the word in a neutral font and white color and performed a Remember/Know test. On the Subjective retrieval task both VPC and DPC were active for recollection compared to familiar items and Correct Rejections. On the Objective retrieval task the DPC was active for all correct old responses. Neither the VPC nor the DPC were significantly active for False Alarms on both the Subjective and Objective tasks. Both VPC and DPC were more active for Subjective Remember compared to Objective Remember response. Neither PPC region was more active for remembering font and color compared to remembering only font or color. Memory load effects for retrieval of information from long-term memory were only seen in the hippocampus on the Subjective retrieval task. These patterns of activity support the role of the VPC in recollection, as seen on the Subjective task, and the role of the DPC in familiarity, as shown in both the Subjective and Objective tasks. The role of the VPC and DPC during recollection and familiarity processing supports both the AtoM and the EB model. The key predictor of the Episodic Buffer model, memory load effects, was not supported and provides the only evidence against one of the two proposed models. Future work should examine the role of the posterior parietal cortex in spontaneous episodic retrieval to assess the validity of the AtoM model. Advanced imaging analysis techniques should be used to determine functional connectivity between the PPC and frontal and temporal memory regions.

Current Signal Detection Theory models of source memory necessitate assumptions about the underlying distributions of source strengths to describe source memory performance. The current experiments applied a modified version of the same-different task in order to plot individual memory stimuli along a controlled dimension of the average frequency of voices. This technique allowed us to determine that subjects were using an independent-observations strategy rather than a differencing strategy when deciding whether two test words were spoken by the same or different female speakers at study. By including two male and two female voices and changing the task distinction from same or different speakers to same or different genders, we predictably switched subjects’ decision strategies. With this new same-different memory design, we are one step closer to ending our reliance on measures that are inferred from data to describe subjects’ source memory performance.