Michael S. Wogalter

Research-based guidelines for warning design and evaluation

During the past two decades, the body of empirical research on warning design and evaluation has grown. Consequently, there are now basic principles and guidelines addressing warning design (e.g., signal words, color, symbols, and text/content), placement (e.g., location within product instructions), and how to enhance the usability of designs by considering factors internal to the user (e.g., beliefs, perceptions of risk, stress). Similarly, evaluation methods have been developed that can be used to measure the effectiveness of warnings such as the degree to which warnings are communicated to recipients and the degree to which they encourage or influence behavioral compliance. An overview of the empirical literature on warning guidelines and evaluation approaches is provided. Researchers, practitioners, and manufacturers can use these guidelines in various contexts to reduce the likelihood that injury and product damage from exposure to a hazard will occur.

Effectiveness of Warnings

The purpose of the present work was to identify some of the factors that influence effectiveness of warnings. Two laboratory experiments designed to examine behavioral effectiveness indicated that a warning placed before procedural instructions is more likely to lead to compliance than a warning that follows instructions. Two rating experiments indicated that for greatest perceived effectiveness, environmental warnings generally require a signal word plus hazard, consequence, and instruction statements. A third rating experiment suggested that informative, nonredundant statements add to a warnings perceived effectiveness. Several field demonstration studies showed that cost of compliance and salience influence behavioral effectiveness. Implications and applications to warning design are discussed.

Comprehension and Memory of Instruction Manual Warnings: Conspicuous Print and Pictorial Icons

Two experiments examined the effects of increasing the noticeability of instruction manual warnings on subsequent comprehension and memory performance. Participants read one of four instruction manuals for a gas-powered electric generator (Experiment 1) or a natural-gas oven (Experiment 2) on the assumption that they would later operate the equipment. The appearance of eight different warning messages in the manuals was altered in two ways: (1) the verbal messages were printed either in conspicuous print (larger text with color highlighting) or in plain print (same as the other text), and (2) either the verbal warning messages were accompanied by compatible pictorial icons or the icons were absent. Results showed that participants who received the conspicuous print, icons present manual better comprehended and recalled the verbal warning messages (Experiments 1 and 2) and better identified the semantic meaning of the icons (Experiment 1) than did participants who received the other three manuals. Implications for the design of instruction manual warnings are discussed.

Reading comprehension in the presence of unattended speech and music

This series of experiments investigated whether the detrimental effects of unattended speech that have been obtained in short-term memory tasks would be obtained in reading comprehension. Such effects would be expected if reading comprehension depends on the maintenance of phonological information in short-term memory. The first three experiments demonstrated that unattended speech but not music interfered with reading comprehension while unattended music had a greater interfering effect than speech on a music identification task. Experiments 4 and 5 showed that the detrimental effect of the speech backgrounds on reading was due to their semantic rather than their phonological properties. The failure to find a phonological interference effect argues against a role for phonological short-term memory in reading comprehension.

Handbook of warnings

Contents: Series Foreword. Foreword. Preface. Part I: Introduction. M.S. Wogalter, Purposes and Scope of Warnings. D. Egilman, S.R. Bohme, A Brief History of Warnings. Part II: Research Methodology. T.L. Smith-Jackson, M.S. Wogalter, Methods and Procedures in Warning Research. D.M. DeJoy, K.A. Cameron, L.J. Della, Postexposure Evaluation of Warning Effectiveness: A Review of Field Studies and Population-Based Research. Part III: Modeling the Process. M.S. Wogalter, Communication-Human Information Processing (C-HIP) Model. M.R. Lehto, Human Factors Models. M.R. Lehto, Optimal Warnings: An Information and Decision Theoretic Perspective. Part IV: Source and Channel Predelivery Aspects. E.P. Cox III, M.S. Wogalter, Warning Source. H.H. Cohen, J. Cohen, C.C. Mendat, M.S. Wogalter, Warning Channel: Modality and Media. Part V: Visual Warnings. M.F. Lesch, Consumer Product Warnings: Research and Recommendations. G.K. Rouseau, M.S. Wogalter, Research on Warning Signs. M.S. Wogalter, N.C. Silver, S.D. Leonard, H. Zaikina, Warning Symbols. R.E. Dewar, Road Warnings With Traffic Control Devices. Part VI: Auditory and Active Warnings. E. Haas, J. Edworthy, An Introduction to Auditory Warnings and Alarms. J. Edworthy, E. Hellier, Complex Nonverbal Auditory Signals and Speech Warnings. J. Meyer, Responses to Dynamic Warnings. J.P. Bliss, C.K. Fallon, Active Warnings: False Alarms. Part VII: Postreception Processing. M.S. Wogalter, W.J. Vigilante, Jr., Attention Switch and Maintenance. H.E. Hancock, C.T. Bowles, W.A. Rogers, A.D. Fisk, Comprehension and Retention of Warning Information. B. Fischhoff, S. Eggers, Mental Models of Warning Decisions: Identifying and Addressing Information Needs. D.M. Riley, Beliefs, Attitudes, and Motivation. K.A. Cameron, D.M. DeJoy, The Persuasive Functions of Warnings: Theory and Models. M.J. Kalsher, K.J. Williams, Behaviorial Compliance: Theory, Methodology, and Results. Part VIII: Individual Differences and Extrinsic Factors. T.L. Smith-Jackson, Receiver Characteristics. A.G. Vredenburgh, I.B. Zackowitz, Expectations. C.B. Mayhorn, K.I. Podany, Warnings and Aging: Describing the Receiver Characteristics of Older Adults. T.L. Smith-Jackson, Culture and Warnings. A.G. Vredenburgh, J. Helmick-Rich, Extrinsic Nonwarning Factors. Part IX: Guidelines From Research. J. Frascara, Typography and the Visual Design of Warnings. E. Hellier, J. Edworthy, Signal Words. K.R. Laughery, Sr., D.P. Smith, Explicit Information in Warnings. Part X: Development Methods. S.L. Young, Hazard Analysis as Part of the Safety Information Development Process. G.M. Peckham, An Overview of the ANSI Z535 Standards for Safety Signs, Labels, and Tags. S.L. Young, J.P. Frantz, T.P. Rhoades, S.M. Hall, Development and Objectives of the ANSI Z535 Series of Standards for Safety Signs and Colors: A Historical Perspective. G.M. Peckham, ISO Design Standards for Safety Signs and Labels. D.A. Johnson, Practical Aspects of Graphics Related to Safety Instructions and Warnings. S.W. Deppa, U.S. and International Standards for Safety Symbols. M.S. Wogalter, V.C. Conzola, W.J. Vigilante, Jr., Applying Usability Engineering Principles to the Design and Testing of Warning Text. N.F. Glasscock, N.T. Dorris, Warning Degradation and Durability. Part XI: Regulations. N.M. Ostrove, Warning Information in the Labeling and Advertising of Pharmaceuticals. S.W. Deppa, Consumer Product Safety Commission: Development of Product Warnings. K.A. Monroe, G. Orr, Warnings and the U.S. Occupational Safety and Health Administration. J.P. Foley, Regulatory Requirements for Motor Vehicle Warnings. A.K. Weyman, An Overview of the Principal U.K. Systems for Safety Warnings and Signage. Part XII: Civil Litigation. M.S. Madden, The Duty to Warn in Products Liability. M.S. Madden, The Quiet Revolution in Post-Sale Duties. M.S. Madden, Warning Duties for Risks to Children. K.R. Laughery, Sr., M.S. Wogalter, The Warning Expert in Civil Litigation. K.J. Williams, M.J. Kalsher, K.R. Laughery, Allocation of Responsibility for Injuries. D.P. Smith, K.J. Williams, M.J. Kalsher, Jury Decision Making in Civil Litigation: Compensatory and Punitive Awards. S.R. Bohme, D. Egilman, Consider the Source: Warnings and Anti-Warnings in the Tobacco, Automobile, Beryllium, and Pharmaceutical Industries. E.P. Cox III, Marketing Versus Warning. Part XIII: Selected Applications and Case Studies. B. Sherehiy, D. Rodrick, W. Karwowski, M.S. Wogalter, Design of Warnings for Physical Tasks: Slips, Trips, Falls, and Manual Materials Handling. D.P. MacKinnon, L. Nohre, Alcohol and Tobacco Warnings. V.L. Neale, T.A. Dingus, Motor Vehicle Warnings. R.B. Williamson, FIRE WARNINGS. H.H. Cohen, J. Pauls, Warnings and Markings for Stairways and Pedestrian Terrain. S.L. Young, J.P. Frantz, T.P. Rhoades, Revisions of Labeling for Personal Watercraft: Label Development and Evaluation. R. Goldsworthy, B. Kaplan, Warning Symbol Development: A Case Study on Teratogen Symbol Design and Evaluation. L.A. Morris, Pharmaceutical Risk Management. C.B. Mayhorn, M-S. Yim, J.A. Orrock, Warnings and Hazard Communications for Natural and Technological Disasters. M.L. Resnick, Risk Communication for Legal, Financial, and Privacy Agreements and Mass Media. M.S. Wogalter, C.B. Mayhorn, The Future of Risk Communication: Technology-Based Warning Systems. J.M. Miller, C. Parent, Appendix: Bibliography of Standards.

Effects of Cost and Social Influence on Warning Compliance

The behavioral effects of cost and social influence on warning compliance were examined. Participants in several studies performed a chemistry laboratory task using a set of instructions that contained a warning directing them to wear a safety mask and gloves. Cost was manipulated by locating the masks and gloves in either an accessible location (low cost) or a less accessible location (high cost); social influence was manipulated by the presence of a confederate who either did or did not comply with the warning. The results showed reduced compliance with the warning when the cost was high and that the compliance rate was biased up or down depending on the behavior of the confederate. The results from a field study confirmed the social influence effect. Implications of this research for facilitating warning effectiveness and safety are discussed.

COMPREHENSION OF PICTORIAL SYMBOLS: EFFECTS OF CONTEXT AND TEST METHOD

This research examined two factors involved in the evaluation of pictorial symbol comprehension: context (absence vs. presence of photographs depicting the probable environments where a symbol would be seen) and test method (multiple-choice with less vs. more plausible distractor alternatives vs. open-ended). We tested 33 pictorial symbols from various sources. The results showed that the multiple-choice test with less plausible distractors inflated comprehension scores by an average of 30% compared with the other two tests, which did not differ. The presence of context increased symbol comprehension in the open-ended test and in the multiple-choice test that had more plausible distractors. Extensive preliminary procedures demonstrated the difficulty of forming a multiple-choice test with plausible distractor alternatives. This fact, combined with multiple-choice tests′ low ecological validity in reflecting the real-world task of symbol comprehension, suggests that this test should be avoided in favor of an open-ended testing procedure. It is suggested that context provides ecologically valid cues that limit the range of possible constructs that the pictorial symbol could be, raising comprehension scores. The use of context may help reduce the costs (money, time, effort) of producing pictorial symbols with acceptable, above-criterion comprehension levels.

Consumer product warnings: The role of hazard perception

Three studies examined factors associated with peoples hazard perceptions of consumer products. A specific interest was how these perceptions relate to willingness to read product warnings. In Study 1, 72 generically-named products were rated on perceived hazard, familiarity, and several expectations associated with warnings, including willingness to read them. Willingness to read warnings was found to have a strong positive relationship with perceived hazard. Though familiarity was negatively related to willingness to read warnings, it provided little predictive value beyond perceived hazard. In addition, products judged as more hazardous were expected to have warnings, to have them in close proximity to the product, and to be less aesthetically impaired by prominent warnings. Since hazard perception was found to be an important determinant of willlingness to read warnings, potential components of hazard perception were examined in Studies 2 and 3. Study 2 showed that perceived severity of injury related more strongly to perceptions of hazard than likelihood of injury. In Study 3, participants generated accident scenarios and rated the severity and likelihood of each scenario. For each product, they also judged overall hazard and their intent to behave cautiously. Results supported the two earlier studies and showed that severity of the first generated scenario was most predictive of hazard perception. Theoretical implications and applications for warning design are discussed.

Alcoholic Beverage Warnings in Magazine and Television Advertisements

Two experiments investigated the impact of warnings in mass-media advertising in print (magazine) or broadcast (television) alcoholic beverage ads. Experiment 1 showed that participants exposed to highly conspicuous warnings in print ads performed better on subsequent memory and knowledge tests than those exposed to less conspicuous warnings. Less conspicuous warnings were generally no better than no warnings. In experiment 2, participants viewing broadcast commercials with both-modality warnings generally performed better than those exposed to voice-only or no warnings. Print-only warnings produced performance equivalent to, or in one case lower than, both-modality warnings. Both experiments show that warnings in ads can communicate information if presented in a salient form.

Behavioural compliance to voice and print warnings

The present research examined the effect of warning modality on compliance behaviour in two laboratory experiments and a field experiment. In the laboratory experiments, subjects followed a set of printed instructions to perform a chemistry demonstration task that involved the measuring and mixing of disguised chemicals. In the first experiment, subjects were directed to wear mask and gloves by a warning presented in one of three ways: printed on the top of the instruction sheet (print-only); given aurally by the experimenter (voice-only); or given both in the printed instructions and by the experimenter (print and voice). The results showed that compliance was significantly higher when the warning was presented in both modalities compared to the print-only condition. The voice-only condition produced intermediate compliance that was not reliably different from the other two conditions. To reduce possible experimenter influence in the voice warning conditions of the first experiment, the warning was prese...