Date of Award

May 2020

Document Type


Degree Name

Master of Science (MS)



Committee Member

Richard Pak

Committee Member

Kelly Caine

Committee Member

Ericka Rovira


High level automation has the ability to relieve operators from complex, working memory-intensive tasks. When the task is primarily perceptual or cognitive in nature, the amount taken over by the machine can be very high. However, as operators interact with technology that is more automated (i.e., automation is higher in stage and degree), they may become more subject to the negative effects when that technology fails. This concept of reaping greater benefits of higher degrees of automation that is reliable but suffering catastrophic performance consequences when it is unreliable has been termed the lumberjack effect and has been well documented among younger adults (Endsley & Kiris, 1995; Onnasch et al., 2013; Rovira et al., 2017). The cause of this effect is that frequent interaction with reliable, high level automation induces a complacency or disengagement with the task (becoming out of the loop). Thus, when that automation fails, the user has been out of the loop (Endsley & Kiris, 1995) and is thus unprepared to resume the task. As older adults have reduced cognitive abilities, they may be even more subject to the lumberjack effect: benefiting greatly with reliable, high level automation but suffering major performance decrements with unreliable automation. The purpose of the current study was to examine the presence and magnitude of the lumberjack effect in older adults as it has not yet been documented in the literature. Older and younger adults interacted with various levels of automation. We replicated the finding that performance was negatively affected on unreliable trials of automation compared to reliable trials for both age groups (i.e., the lumberjack effect). However, this effect only appeared during low workload conditions and did not appear to be more pronounced in older adults. These results are the first to show that the lumberjack effect, previously observed in younger adults is equally pronounced in older adults. However, what aspect of aging cognition was the source of this similar lumberjack effect is still an empirical question. Future work should be done to understand methods which can help older adults stay in the loop when using automated technology.



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