Detrending Changes the Temporal Dynamics of a Semantic Fluency Task.
Objective: To study the dynamics of clustering semantic fluency responses and switching between clusters.Methods: We conducted a cross-sectional study of participants (N= 60) in a study of patient reported outcomes who were given the Saint Louis University Mental Status test. Sixty-second animal naming tests were scored for the timing of responses as well as the clustering of responses into semantic categories. Time scores were detrended to correct for exponential exhaustion and normalize the time scale across individuals.Results: Grouped by number of responses given, low performers (LP; Carter et al., 2012) switched between clusters fewer times than medium performers (MP) and high performers (HP). Prior to detrending, LP showed increased intracluster response times when compared to the other groups, but no differences were shown in intercluster response times. After detrending, however, the difference in intracluster response times disappeared and LP showed significantly faster detrended intercluster response times compared to both MP and HP.Conclusion: Prior to detrending, slower intracluster response times appear to be driving poorer performance. When time scores are detrended, our findings suggest that LP participants have quicker intercluster response times but exhaust more quickly as well. Detrending can help describe the interplay between the structure-loss and retrieval-slowing models of declining semantic fluency by isolating the component mechanisms involved in each.
School of Medicine, Case Western Reserve University Cleveland, OH, USA.
Steven
S
Lenio
School of Medicine, Case Western Reserve University Cleveland, OH, USA.
Frances M
FM
Lissemore
School of Medicine, Case Western Reserve UniversityCleveland, OH, USA; Departments of Psychiatry and Neurology, University Hospitals Cleveland Medical CenterCleveland, OH, USA.
Martha
M
Sajatovic
School of Medicine, Case Western Reserve University Cleveland, OH, USA.
Kathleen A
KA
Smyth
School of Medicine, Case Western Reserve University Cleveland, OH, USA.
Curtis
C
Tatsuoka
Department of Mathematics, Applied Mathematics and Statistics, and Center for Stochastic and Chaotic Processes in Science and Technology, Case Western Reserve University Cleveland, OH, USA.
Wojbor A
WA
Woyczynski
School of Medicine, Case Western Reserve University Cleveland, OH, USA.
Alan J
AJ
Lerner
Alzheimer’s disease; Weibull distribution; cluster-switch analysis; cognitive impairment; semantic fluency testing; semantic memory