Visible Vibrations (originally Chladni Patterns) Joshua Gutwill July 2002 Keywords: < formative complexity exhibit observation video audio > 1
Visible Vibrations (originally Chladni Patterns) Formative Evaluation Report Joshua Gutwill 7/9/02 Goals To determine, over the course of three modifications to the exhibit, whether: visitor holding time increased visitors were more successful in making a pattern visitors made more patterns visitors used more plates Summary There were no differences across groups. However, the exhibit seems to be working well. Methods We compared three versions of the exhibit: Single Plate with Thogerson s label N = 32 visitor groups in two hours of tape, recorded on 3/17/02 Three plates with Burk s label N = 24 visitor groups in 4 hours of tape (half hour per tape), recorded on 6/29/02 Seven plates with Burk s label N = 25 visitor groups in 4 hours of tape (half hour per tape), recorded on 6/29/02 Table 1. Three versions of exhibit tested in this study Single Plate Three plates 2 Seven plates
Analysis consists of coding 6 one-hour videotapes recorded on 3/17/02 (2 tapes) and 6/29/02 (4 tapes). Results Visitor holding time There were no statistically significant differences in mean holding time across the three versions (F 78 = 1.3, p =.27). Nonetheless, the holding times were quite high across all versions. The median holding times were: Single Plate Version = 3 minutes, 0 seconds Three Plates Version = 4 minutes, 0 seconds Seven Plates Version = 3 minutes, 48 seconds See Figure 1 for holding time distributions for all three groups. Note that the distributions are not very right-skewed, but are almost normal. This is unusual for a museum exhibit. Chladni patterns Single plate Three plates Seven plates 25% 20% 15% 10% 5% 0% Time (min:sec) Figure 1. Holding times for different visitor groups across versions. The differences in holding times are not significant. 3
Success in making a pattern There were no significant version differences in the number of visitor groups who were able to make a pattern. In all three versions, approximately 75% of the visitor groups were able to make at least one sharp pattern in the sand. Making multiple patterns There were no significant differences across version in the number of patterns made by each visitor group. On average, each visitor group made about 2 patterns, regardless of the number of plates available at the exhibit. The percentage of visitor groups making more than one pattern was not statistically different across versions (χ2 = 1.7, p =.44): Single Plate Version = 50% made more than one pattern Three Plates Version = 58% made more than one pattern Seven Plates Version = 40% made more than one pattern Table 2 shows the number of visitors making patterns in each treatment group. Table 2. Patterns made by visitor groups in different versions. Version Patterns made Single Plate N = 32 Three Plates N = 24 Seven Plates N = 25 0 25% 25% 24% 1 25% 17% 36% 2 16% 25% 24% 3 19% 17% 0% 4 13% 4% 8% 5 3% 8% 0% 6 0% 4% 4% 15 0% 0% 4% Using multiple plates There were no significant differences in the number of plates used by visitors in the Three Plates Version and the Seven Plates Version (the Single Plate Version is excluded from this analysis). On average, visitor groups in both versions used about 2 plates. Two visitors used 5 plates; the rest of the visitors used 1 to 3 plates. 4
Conclusion The exhibit seems to be working well. Although there have been few changes in visitors behaviors across versions, it is clear that the exhibit is holding visitors for a lengthy amount of time (about 4 minutes, on average). In addition, most visitors are able to make patterns, and most visitors in the Three Plates version made multiple patterns. Anecdotally, Diane Burk s label seems to work quite well. I noticed very few visitors having difficulty understanding what to do. For instance, very few visitors put too much sand on the plate, a common problem with the Single Plate (Thogerson s label) version of the exhibit. Although there were no significant differences between the Three Plates and Seven Plates Versions, I would recommend including only 3 plates at the exhibit. Only 2 out of 49 visitor groups used more than 3 plates, and visitors in the Three Plates Version seemed more prone to making multiple patterns. However, this is not a strong recommendation. Acknowledgments I would like to thank Nina Hido, Valerie Sununu and Steve Tokar for collecting the data, and Suzanne Buennagel and Steve Tokar for coding visitors behaviors. This material is based upon work supported by the National Science Foundation under Grant number 0087844. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. 5