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Systematics Section / ASPT

Kirchoff, Bruce K. [1], Richter, Scott [2].

A Contribution to Solving the Problem of Morphological Character States.

The problem of creating reliable and valid morphological character states can be solved by applying insights from cognitive psychology to the task of character state creation. Cognitive psychologists have identified two visual processing modes. Analytic processing involves attending to distinct, separate features of a trait (e.g., the nose, eyes, and mouth of a face). Holistic processing involves attending to global features such as overall shape (Gestalt), or to interdependent aspects such as the distance between features. We present preliminary evidence that holistic visual processors are able to create character states that have higher inter-investigator agreement (higher reliability), and higher agreement with an independent assessment of phylogeny (greater validity), than analytic processors. Participants in our studies were either undergraduate biology students recruited from an intermediate plant biology class, or trained plant morphologists. The undergraduates were divided into control and experimental groups. The experimental group received training with the traits before the character state creation step. Neither the control group nor the morphologists received any training with the traits. Training has been shown to move participants from analytic to holistic processing in a given perceptual domain. To create the character states, photographs were laid out on a table and sorted into two clusters whose members were most similar to each other. Similarity was assessed differently by trained and untrained participants, and was consistent with the hypothesis that the different groups were used analytic (untrained groups) versus holistic (trained group) processing. Dichotomous sorting continued until each cluster contained only one or two traits. This procedure produced a hierarchical "character cladogram" of traits for each participant. These character cladograms were compared with others from the same treatment group, and with an independent assessment of phylogeny. The results were consistent with the hypothesis that holistic processors produce character states with higher reliability and validity.

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1 - University of North Carolina Greensboro, Department of Biology, Po Box 26170, Greensboro, North Carolina, 27402-6170, USA
2 - University of North Carolina at Greensboro, Department of Mathematics, Greensboro, North Carolina, 27402

character state
cognitive psychology

Presentation Type: Oral Paper
Session: 38-3
Location: 400/Hilton
Date: Tuesday, August 16th, 2005
Time: 2:30 PM
Abstract ID:5

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