Although it is well established that persons with traumatic brain injury (TBI) experience word retrieval difficulties, the underlying cause of these deficits is not known. Difficulties with word retrieval have negative social implications as they can impact on the ability to converse with others. The overarching goal of this dissertation was to determine the underlying cause of problems with word retrieval after TBI. To test word retrieval in this dissertation, participants were given a series of word fluency tasks and the speed of word generation was measured. In addition to measuring interresponse times, procedures used by Rohrer, Wixted, Salmon and Butters (1995) were also followed. This involved the calculation of parameter estimates to investigate whether slowed retrieval or degraded semantic stores were responsible for the patients� word retrieval difficulties. One parameter (N) was a measure of the total number of retrievable words and the second parameter (tau) was an estimate of mean latency. Study 1 was designed to trial the procedure and equipment adopted throughout this dissertation to analyse speech. University students were presented with categories on a computer screen and asked to generate as many exemplars as possible in 60 seconds. A PowerLab Chart sound system was used to measure the time that each word was generated. The results of Study 1 showed that the methodology of previous research could be replicated using the PowerLab Chart sound system. In Study 2, persons with postconcussion syndrome (PCS) and matched controls were given two word fluency tasks. Results showed that on both tasks patients recalled fewer words, had longer pauses between words, and took significantly longer to generate their first word than controls. Also, patients had a significantly reduced N relative to controls, but there was no difference in tau between patients and controls. Given that the participants had not finished responding and that parameter estimates require responses to be exhausted, Study 3 was designed to replicate the findings of Study 2 using an extended recall period. In Study 3, patients with PCS and matched controls completed a series of word fluency tasks and were given extended periods of time to generate words. Results showed that the patients obtained significantly fewer words on two of the tasks, but no evidence of slowed retrieval was found. There was also no difference in the estimates of N and tau between patients and controls. As the patients in Study 3 sustained more minor injuries than those in Study 2, Study 4 tested patients with severe TBI. In Study 4, patients with severe TBI and matched controls were given a series of word fluency tasks. Results showed that the patients generated fewer words and experienced slowed retrieval. Again, there was no difference in the estimates of N and tau between patients and controls. The results of Study 4 confirmed the hypothesis that slowed word retrieval is a consequence of TBI. Taken together, the results of this dissertation show that an underlying slowness of processing is the primary cause of problems with word retrieval in persons with TBI.

Thesis (MPsy(Clinical))--University of South Australia, 2002.

Thesis (MPsy(Clinical))--University of South Australia, 2002.

Doctor of Philosphy (PhD) / Agitation following traumatic brain injury (TBI) is characterised by a heightened state of activity with disorganised information processing that interferes with learning and achieving functional goals. This thesis outlines a series of studies across four research phases, investigating how occupational performance of adults with TBI is affected by agitated behaviour and information processing difficulties. Clinicians report the presence of agitation interferes with engagement in therapy and achievement of rehabilitation goals. Research Phase One used a retrospective chart review of 80 adults with severe TBI to identify a high incidence of agitated behaviour during inpatient TBI rehabilitation. Agitated behaviour was associated with lengthier rehabilitation admission, prolonged duration of post-traumatic amnesia (PTA), and poor cognitive functioning at discharge. The association between agitation and poor cognition persisted for at least two years after discharge, highlighting the significant impact of agitated behaviour on people’s ability to relearn cognitive skills for daily function. These initial research findings directed subsequent research phases, in which an information processing model was adopted to examine application of cognitive strategies during occupational performance. An emerging occupational therapy assessment, The Perceive, Recall, Plan and Perform (PRPP) System of Task Analysis, was selected as the primary method for evaluating how application of cognitive strategies during occupational performance is affected in agitated patients. Clinical utility of this measure was established in a case study of an adult demonstrating severely agitated behaviour during inpatient TBI rehabilitation, followed by examination of instrument reliability and validity with ten experienced occupational therapists and five adults with agitated behaviour following brain injury. The PRPP System of Task Analysis emerged as a valid and reliable method for determining strategy application deficits during occupational performance of adults with agitated behaviour, in acute stages of TBI rehabilitation. Consistent patterns of processing deficits were related to the Perceive and Recall Quadrants of the PRPP System. The assessment tool forms part of a dynamic, interactive assessment and intervention system. The PRPP System of Intervention was evaluated in the final research phase, using an experimental single case design with replication across eight adults. The effectiveness of PRPP Intervention was examined in comparison to conventional occupational therapy in an ABAB design. Efficacy of the PRPP Intervention was demonstrated, with patients applying significantly more information processing strategies to occupational performance tasks during PRPP Intervention than during conventional occupational therapy sessions. Agitated behaviour concurrently reduced over the period of the study. Relationships between information processing and agitated behaviour are hypothesised.

Current theories of PTSD propose that impaired retrieval of trauma memories may impede processing of these memories and subsequent trauma recovery. This thesis investigated memory retrieval processes in trauma survivors with and without symptoms of posttraumatic stress, and in non-traumatised individuals exposed to a highly arousing event. Study 1 examined deliberate avoidance of unwanted memories in recent trauma survivors. The results indicated that attempts to forget were associated with poorer recall of forgotten information, but the size of this effect did not depend on the presence or absence of Acute Stress Disorder (ASD). Study 2 investigated automatic retrieval inhibition in trauma survivors with or without Posttraumatic Stress Disorder (PTSD). The results suggested that repeated retrieval of trauma-related information by individuals with PTSD can cause inhibition of related, but unpractised information. Studies 3 and 4 examined the relationship between the vantage point of trauma memories, avoidance and posttraumatic stress symptomatology. The findings indicated that recalling a traumatic event from an observer perspective is associated with post trauma avoidance. They also showed that an observer vantage point in the initial few weeks after trauma is associated with poorer long-term post trauma adjustment. Studies 5, 6 and 7 were analogue studies which analysed the impact of heightened arousal on memory retrieval in novice skydivers. The results suggested that elevated arousal can interfere with retrieval of information related to the arousal-inducing event. Study 7 also indicated that autobiographical memory for the event may be impaired. Finally, Study 8 examined the qualities of trauma memories that were accessed via different modes of retrieval. The results provided evidence that intrusive memories were experienced as more realistic and with more intense affect than memories for the same event that were deliberately retrieved. Together, the findings of this program of research extend current theories of PTSD by highlighting the mechanisms through which retrieval of trauma memories may be impaired. The results suggest that the quality of trauma memories is affected by avoidance processes, elevated arousal and level of conscious control the individual exerts over retrieval.

Current theories of PTSD propose that impaired retrieval of trauma memories may impede processing of these memories and subsequent trauma recovery. This thesis investigated memory retrieval processes in trauma survivors with and without symptoms of posttraumatic stress, and in non-traumatised individuals exposed to a highly arousing event. Study 1 examined deliberate avoidance of unwanted memories in recent trauma survivors. The results indicated that attempts to forget were associated with poorer recall of forgotten information, but the size of this effect did not depend on the presence or absence of Acute Stress Disorder (ASD). Study 2 investigated automatic retrieval inhibition in trauma survivors with or without Posttraumatic Stress Disorder (PTSD). The results suggested that repeated retrieval of trauma-related information by individuals with PTSD can cause inhibition of related, but unpractised information. Studies 3 and 4 examined the relationship between the vantage point of trauma memories, avoidance and posttraumatic stress symptomatology. The findings indicated that recalling a traumatic event from an observer perspective is associated with post trauma avoidance. They also showed that an observer vantage point in the initial few weeks after trauma is associated with poorer long-term post trauma adjustment. Studies 5, 6 and 7 were analogue studies which analysed the impact of heightened arousal on memory retrieval in novice skydivers. The results suggested that elevated arousal can interfere with retrieval of information related to the arousal-inducing event. Study 7 also indicated that autobiographical memory for the event may be impaired. Finally, Study 8 examined the qualities of trauma memories that were accessed via different modes of retrieval. The results provided evidence that intrusive memories were experienced as more realistic and with more intense affect than memories for the same event that were deliberately retrieved. Together, the findings of this program of research extend current theories of PTSD by highlighting the mechanisms through which retrieval of trauma memories may be impaired. The results suggest that the quality of trauma memories is affected by avoidance processes, elevated arousal and level of conscious control the individual exerts over retrieval.

Current theories of PTSD propose that impaired retrieval of trauma memories may impede processing of these memories and subsequent trauma recovery. This thesis investigated memory retrieval processes in trauma survivors with and without symptoms of posttraumatic stress, and in non-traumatised individuals exposed to a highly arousing event. Study 1 examined deliberate avoidance of unwanted memories in recent trauma survivors. The results indicated that attempts to forget were associated with poorer recall of forgotten information, but the size of this effect did not depend on the presence or absence of Acute Stress Disorder (ASD). Study 2 investigated automatic retrieval inhibition in trauma survivors with or without Posttraumatic Stress Disorder (PTSD). The results suggested that repeated retrieval of trauma-related information by individuals with PTSD can cause inhibition of related, but unpractised information. Studies 3 and 4 examined the relationship between the vantage point of trauma memories, avoidance and posttraumatic stress symptomatology. The findings indicated that recalling a traumatic event from an observer perspective is associated with post trauma avoidance. They also showed that an observer vantage point in the initial few weeks after trauma is associated with poorer long-term post trauma adjustment. Studies 5, 6 and 7 were analogue studies which analysed the impact of heightened arousal on memory retrieval in novice skydivers. The results suggested that elevated arousal can interfere with retrieval of information related to the arousal-inducing event. Study 7 also indicated that autobiographical memory for the event may be impaired. Finally, Study 8 examined the qualities of trauma memories that were accessed via different modes of retrieval. The results provided evidence that intrusive memories were experienced as more realistic and with more intense affect than memories for the same event that were deliberately retrieved. Together, the findings of this program of research extend current theories of PTSD by highlighting the mechanisms through which retrieval of trauma memories may be impaired. The results suggest that the quality of trauma memories is affected by avoidance processes, elevated arousal and level of conscious control the individual exerts over retrieval.

Current theories of PTSD propose that impaired retrieval of trauma memories may impede processing of these memories and subsequent trauma recovery. This thesis investigated memory retrieval processes in trauma survivors with and without symptoms of posttraumatic stress, and in non-traumatised individuals exposed to a highly arousing event. Study 1 examined deliberate avoidance of unwanted memories in recent trauma survivors. The results indicated that attempts to forget were associated with poorer recall of forgotten information, but the size of this effect did not depend on the presence or absence of Acute Stress Disorder (ASD). Study 2 investigated automatic retrieval inhibition in trauma survivors with or without Posttraumatic Stress Disorder (PTSD). The results suggested that repeated retrieval of trauma-related information by individuals with PTSD can cause inhibition of related, but unpractised information. Studies 3 and 4 examined the relationship between the vantage point of trauma memories, avoidance and posttraumatic stress symptomatology. The findings indicated that recalling a traumatic event from an observer perspective is associated with post trauma avoidance. They also showed that an observer vantage point in the initial few weeks after trauma is associated with poorer long-term post trauma adjustment. Studies 5, 6 and 7 were analogue studies which analysed the impact of heightened arousal on memory retrieval in novice skydivers. The results suggested that elevated arousal can interfere with retrieval of information related to the arousal-inducing event. Study 7 also indicated that autobiographical memory for the event may be impaired. Finally, Study 8 examined the qualities of trauma memories that were accessed via different modes of retrieval. The results provided evidence that intrusive memories were experienced as more realistic and with more intense affect than memories for the same event that were deliberately retrieved. Together, the findings of this program of research extend current theories of PTSD by highlighting the mechanisms through which retrieval of trauma memories may be impaired. The results suggest that the quality of trauma memories is affected by avoidance processes, elevated arousal and level of conscious control the individual exerts over retrieval.

Current theories of PTSD propose that impaired retrieval of trauma memories may impede processing of these memories and subsequent trauma recovery. This thesis investigated memory retrieval processes in trauma survivors with and without symptoms of posttraumatic stress, and in non-traumatised individuals exposed to a highly arousing event. Study 1 examined deliberate avoidance of unwanted memories in recent trauma survivors. The results indicated that attempts to forget were associated with poorer recall of forgotten information, but the size of this effect did not depend on the presence or absence of Acute Stress Disorder (ASD). Study 2 investigated automatic retrieval inhibition in trauma survivors with or without Posttraumatic Stress Disorder (PTSD). The results suggested that repeated retrieval of trauma-related information by individuals with PTSD can cause inhibition of related, but unpractised information. Studies 3 and 4 examined the relationship between the vantage point of trauma memories, avoidance and posttraumatic stress symptomatology. The findings indicated that recalling a traumatic event from an observer perspective is associated with post trauma avoidance. They also showed that an observer vantage point in the initial few weeks after trauma is associated with poorer long-term post trauma adjustment. Studies 5, 6 and 7 were analogue studies which analysed the impact of heightened arousal on memory retrieval in novice skydivers. The results suggested that elevated arousal can interfere with retrieval of information related to the arousal-inducing event. Study 7 also indicated that autobiographical memory for the event may be impaired. Finally, Study 8 examined the qualities of trauma memories that were accessed via different modes of retrieval. The results provided evidence that intrusive memories were experienced as more realistic and with more intense affect than memories for the same event that were deliberately retrieved. Together, the findings of this program of research extend current theories of PTSD by highlighting the mechanisms through which retrieval of trauma memories may be impaired. The results suggest that the quality of trauma memories is affected by avoidance processes, elevated arousal and level of conscious control the individual exerts over retrieval.

Doctor of Philosphy (PhD) / Agitation following traumatic brain injury (TBI) is characterised by a heightened state of activity with disorganised information processing that interferes with learning and achieving functional goals. This thesis outlines a series of studies across four research phases, investigating how occupational performance of adults with TBI is affected by agitated behaviour and information processing difficulties. Clinicians report the presence of agitation interferes with engagement in therapy and achievement of rehabilitation goals. Research Phase One used a retrospective chart review of 80 adults with severe TBI to identify a high incidence of agitated behaviour during inpatient TBI rehabilitation. Agitated behaviour was associated with lengthier rehabilitation admission, prolonged duration of post-traumatic amnesia (PTA), and poor cognitive functioning at discharge. The association between agitation and poor cognition persisted for at least two years after discharge, highlighting the significant impact of agitated behaviour on people’s ability to relearn cognitive skills for daily function. These initial research findings directed subsequent research phases, in which an information processing model was adopted to examine application of cognitive strategies during occupational performance. An emerging occupational therapy assessment, The Perceive, Recall, Plan and Perform (PRPP) System of Task Analysis, was selected as the primary method for evaluating how application of cognitive strategies during occupational performance is affected in agitated patients. Clinical utility of this measure was established in a case study of an adult demonstrating severely agitated behaviour during inpatient TBI rehabilitation, followed by examination of instrument reliability and validity with ten experienced occupational therapists and five adults with agitated behaviour following brain injury. The PRPP System of Task Analysis emerged as a valid and reliable method for determining strategy application deficits during occupational performance of adults with agitated behaviour, in acute stages of TBI rehabilitation. Consistent patterns of processing deficits were related to the Perceive and Recall Quadrants of the PRPP System. The assessment tool forms part of a dynamic, interactive assessment and intervention system. The PRPP System of Intervention was evaluated in the final research phase, using an experimental single case design with replication across eight adults. The effectiveness of PRPP Intervention was examined in comparison to conventional occupational therapy in an ABAB design. Efficacy of the PRPP Intervention was demonstrated, with patients applying significantly more information processing strategies to occupational performance tasks during PRPP Intervention than during conventional occupational therapy sessions. Agitated behaviour concurrently reduced over the period of the study. Relationships between information processing and agitated behaviour are hypothesised.