Benjamin, Jr., for his mentoring, support, and feedback on this project. It would not have come to fruition without his guidance. 2. PowerPoint slides introducing and using these activities are available on request.

The equivalence of visual and auditory scatterplots was examined in two experiments. Experiment 1 examined the relationship between actual Pearson's r and visual and auditory judgments of direction and magnitude of correlation for 24 bivariate data samples. Experiment 2 directly evaluated visual and auditory perceptual sensitivity to outliers by examining changes in perceived magnitude and direction of correlation estimates for scatterplots from Experiment 1 that were altered by the addition of outlier points. Results suggest that the information conveyed by visual and auditory scatterplots is used very similarly by the two modalities. Both visual and auditory scatterplots are quite efficient in conveying sign and magnitude of correlation, and the effect of outliers on judged magnitude of correlation is similar for the two types of data display.

The equivalence of visual and auditory graphical displays was examined in two experiments. In Experiment 1, multidimensional scaling techniques were applied to paired comparison similarity judgments of both auditory and visual displays of simple periodic wave forms. In Experiment 2, a subset of perceptually similar pairs of wave forms was selected as the stimulus set for an AB-X discrimination task in both auditory and visual modalities. Results suggest much greater apparent visualauditory equivalence for the similarity rating task than for the more difficult discrimination task, implying that one should consider the demands of the task when deciding whether auditory graphic displays are suitable alternatives to more traditional visual displays.Advances in computer technology offer possibilities for data summary and presentation in highly nontraditional formats. Flowers and Hauer (1992, 1993, 1995 have demonstrated that the perceptual structures ofvision and audition are highly similar for the representation ofgraphs depicting statistical distribution and time series functions. The present investigation was designed to extend previous research to a new form ofdata: periodic wave forms.This project included both an assessment of visualauditory perceptual equivalence for these graphs (based on similarity ratings) and an assessment of the equivalence of accuracy performance for the two modalities on a more demanding AB-X discrimination task. If auditory displays are to be used as substitutes for visual graphics, it is necessary to assess the degree of accuracy achievable by the two modalities for demanding tasks such as discriminating between different data sets. Knowing the relative performance levels of the two modalities for such discriminations is useful in decisions about the appropriateness of auditory graphics in general, the optimal design of auditory displays, and the appropriate measures for training people to use them. EXPERIMENT!In this study, we assessed whether the degree ofvisualauditory perceptual equivalence ofthese wave-form stimCorrespondenceshould be addressed to K. D. Turnage,Department of Psychology, 209 Burnett Hall, University of Nebraska, Lincoln, NE 68588-0308. uli would parallel the perceptual equivalence reported for other types of graphs. If wave-form data are as suitable for auditory presentation as distributional and trend data are, visual and auditory perceptions of these stimuli should be very equivalent. MethodSubjects. Twenty-six undergraduate psychology students who reported having normal or corrected-to-normal vision and hearing participated to fulfill a course research requirement. Thirteen subjects (balanced for gender) participated in each modality condition.Materials. Eighteen data samples, each consisting of 100 numbers that described a periodic wave-form function, were computer generated. These 18 wave forms varied in shape (sine, square, and a composite, which was a weighted sum ofthe two), frequency (low, medium, and high, which were 4, 6, and 8 cycles per 100 points, re...

The design of auditory formats for data display is presently focused on applications for blind or visually impaired users, specialized displays for use when visual attention must be devoted to other tasks, and some innovative work in revealing properties of complex data that may not be effectively rendered by traditional visual means. With the availability of high-quality and flexible sound production hardware in standard desktop computers, the potential exists for using sound to represent characteristics of typical "small and simple" samples of data in routine data inspection and analysis. Our research has shown that basic properties of simple functions, distribution properties of data samples, and patterns of covariation between two variables can be effectively displayed by simple auditory graphs involving patterns of pitch variation over time. While such developments have implications for specialized applications and populations of users, these displays are easily comprehended by normal users with minimal practice. Providing further software enhancement to encourage exploration of data representation by sound may lead to a variety of useful creative developments in data display technology.

Sonification tools have not yet become typical components of data analysis software, despite dramatic advances in sound-production capabilities of personal computers over the past decade. However, we continue to believe that auditory displays have the potential to be highly useful for "small scale" exploration of data for normally sighted users as well as an alternative format for users with visual impairment. Demonstration of effective examples of auditory data displays and design of flexible software tools for data sonification will be key factors in determining the impact of this method of data representation.