The integrity of Web-delivered experiments: can you trust the data?

Data from Web-delivered experiments conducted in browsers by remote users of PsychExperiments, a public on-line psychology laboratory, reveal experiment effects that mirror lab-based findings, even for experiments that require nearly millisecond accuracy of displays and responses. Textbook results are obtained not just for within-subjects effects, but for between-subjects effects as well. These results suggest that existing technology is adequate to permit Web delivery of many cognitive and social psychological experiments and that the added noise created by having participants in different settings using different computers is easily compensated for by the sample sizes achievable with Web delivery.