Commonly employed executive function measures may be of limited use due to their modest ecological validity. A novel task was developed - the Multitasking in the City Test (MCT) - in an attempt to improve ecological validity. The MCT involves task demands that resemble the demands of everyday activities. In study one, healthy participants were recruited in order to explore ‘normal’ performance on the MCT and its relationship with other cognitive measures. The MCT showed poor associations with executive tests and significant correlations with non-executive tests. This suggested the MCT may evaluate executive functioning in a different way from other executive measures such that it does not simply measure component executive processes but the integration of these components into meaningful behaviour. Patients with stroke and traumatic brain injury were recruited for study two to further explore the ecological validity and MCT performance characteristics. Only the MCT and a semantic fluency task demonstrated good ecological validity via significant relationships with a behavioural rating scale. Patients and normals made qualitatively similar types of errors although patients made these errors more frequently. Patients demonstrated better planning ability but completed fewer tasks than normals on the MCT. This discrepancy was attributed to impaired initiation. In study three, the MCT and verbal fluency tasks were administered to brain-injured individuals both pre- and post-executive function rehabilitation to evaluate their utility as treatment outcome measures and to assess ecological validity via a different behavioural rating scale from the one used in study two. Strategies trained during treatment generalized to MCT but not verbal fluency performance. Both MCT and semantic fluency performance were found to have good ecological validity. Overall, the findings from this research project suggest the MCT and semantic fluency tasks have good ecological validity. They further suggest that several common executive function measures lack adequate ecological validity and may not be predictive of real world behaviour. Moreover, these results support the concept of an executive function ‘system’ that can be fractionated into a variety of executive processes and that impairments in one process (e.g., initiation) can exist alongside intact functioning in other processes (e.g., planning).
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OTU.1807/26194 |
| Date | 15 February 2011 |
| Creators | Jovanovski, Diana |
| Contributors | Zakzanis, Konstantine |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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