To help promote the development of better cognitive rehabilitation techniques, we believe it is important to go beyond assessment of the presence or absence of cognitive disabilities, to specify at a foundational level the nature of deficits. As an example, using model-based cognitive science paradigms, our work has shown that severe TBI patients’ episodic memory deficits are unlikely to reflect inefficient retrieval inhibition, resource capacity limitations, or metamemorial deficits. This laboratory has also provided data to suggest that momentary lapses of intention may underlie severe TBI participants’ event-based prospective memory failures, and that memory difficulties may affect the narrative comprehension abilities of TBI participants by increasing their tendency to focus on the focal sentence at the expense of integrating the larger discourse. Regarding rehabilitation, our research suggests that implicit and automatic processes could be exploited in rehabilitation with TBI patients who are more than one-year post injury. For example, our work has shown that in contrast to controlled (attention-demanding) processes, implicit learning and memory mechanisms as well as well-learned automatic processes (e.g., semantic activation) are relatively intact by one-year following severe TBI. Our skill learning research also suggests that rehabilitation programs should try to capitalize on processes that can be made automatic through practice. For example, similar to controls, we found that at one-year post-injury severe TBI patients can successfully automatize components of attention-demanding cognitive tasks through consistent practice, and they can retain this automatized skill over a long-term retention interval without practice (i.e., 5-10 months).
Currently, however, there is a gap in our understanding of automatic processes and skill development abilities during the period of early recovery from a TBI, the time at which most inpatient cognitive rehabilitation work occurs. There is also no empirically supported theory about cognitive recovery following TBI to guide intervention strategies. We are currently completing several projects that are designed to provide better scientific evidence to guide cognitive rehabilitation by more fully characterizing the potential early-learning mechanisms of TBI patients, and by prospectively evaluating the recovery trajectories of both automatic and controlled cognitive processes. Participants with TBI and controls are completing experimental tasks designed to assess automatic and more controlled components of visual search, semantic priming, and memory. These task are being administered following the TBI patients emergence from post-traumatic amnesia (PTA), and then again at 2-, 6-, and 12-month follow-up intervals. Preliminary data suggests that for a large subset of participants with TBI, these well-learned automatic cognitive processes are intact following emergence from PTA. Perceptually-based implicit learning abilities and memory-based skill learning abilities are also being evaluated in the earliest phases of recovery. We are also tracking the recovery of other less studied but important cognitive processes, including time perception, prospective memory, temporal order memory, focused attention, and metamemorial abilities. Baseline data analysis indicates that post-acute TBI participants make significantly more prospective memory errors, and that they underestimate time intervals to a greater extent than controls when time estimations occur outside of immediate memory capacity (i.e., over 30 seconds).