Effects of frequency and similarity neighborhoods on pharmacists’ visual perception of drug names
Introduction
Recent estimates suggest that medical errors of all types may cause the death of between 44,000 and 98,000 hospitalized patients in the United States each year (Kohn, Corrigan, & Donaldson, 2000). Errors involving medication cause the death of one person every day in the US, and injure more than a million more each year (US Food and Drug Administration, 2001). Confusions between drug names that look and sound alike account for between 15% and 25% of reported medication errors in the US (US Pharmacopeia (1995), US Pharmacopeia (1996), US Pharmacopeia (2001)). Similarity between drug names can cause errors in short-term memory as well as in visual and auditory perception (Brodell, Helms, KrishnaRao, & Bredle, 1997; Lambert, Chang, & Lin, 2001b; Lambert, Chang, Lin, & Gupta, 2000; Lambert, Lin, Gandhi, & Chang, 1999; Luce & Pisoni, 1998; Luce, 1959). This investigation examined the effect of similarity and prescribing frequency on pharmacists’ ability to accurately identify blurry, briefly presented, handwritten and typewritten drug names. Two research questions provided the motivation for the experiments that follow:
(1) To what extent is a pharmacist's ability to identify a target drug name affected by the prescribing frequency of the target, the number of names similar to the target, and the prescribing frequency of the similar names?
(2) To what extent do the characteristics in Q1 have different effects depending on whether the drug name is handwritten or typewritten?
Section snippets
Activation-competition models of visual perception
The “interactive activation” framework has been very influential in the development of cognitive psychology theories of visual word recognition, following a seminal formulation of this approach by McClelland and Rumelhart (McClelland & Rumelhart, 1981; Rumelhart & McClelland, 1982). In such a model, words are represented in memory as networks of nodes connected by excitatory and inhibitory links. The nodes are typically arranged in a hierarchy of levels. Lower level nodes detect particular
Design
This experiment was designed to examine the effect of prescribing frequency, neighborhood frequency and neighborhood density on the probability of a pharmacist making an error in a visual perceptual identification task. Participants viewed a series of noise-masked, typewritten drug names as they were briefly presented on a computer monitor. The task was to correctly identify the presented name by typing it into a provided text box. All experiments were approved in advance by the local
Design
The design of Experiment 2 was identical to that used in Experiment 1 except that in this experiment, handwritten drug names were used as stimuli instead of typewritten names (Brodell et al., 1997). This experiment also used a slightly different type of degradation (described below).
Participants
Participants were 37 licensed, practicing, community pharmacists recruited from the exhibit halls and corridors of the 2000 annual meeting of the National Community Pharmacists Association in San Antonio, Texas. All
General discussion
Drug name confusions are a persistent source of medication errors and an ongoing threat to patient safety. In spite of all that has been written and all the remedial steps that have been taken recently, new pairs of confusing names continue to appear regularly (Institute for Safe Medication Practices, 2002). One way to minimize the incidence of these errors is to equip decision-makers in the pharmaceutical industry and the FDA with tools to make better name-approval decisions. Such tools should
Acknowledgements
This research was supported in part by the National Patient Safety Foundation and by the Latiolais Leadership Fund of the Ohio State University. The authors acknowledge the assistance of Bill Brewer, Mike Cohen, Gary Dell, Robert Gibbons, David Lambert, Eric Lambert, Robert Lee, Swu-Jane Lin, Paul Luce, Susan Proulx, Don Rucker, and Gordon Schiff. We are also indebted to the volunteer participants from the American Pharmaceutical Association and the National Community Pharmacists Association.
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