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

Data from Web-delivered experiments conducted in browsers by remote users o f PsychExperiments, a public on-line psychology laboratory, reveal experime nt effects that mirror lab-based findings, even for experiments that requir e nearly millisecond accuracy of displays and responses. Textbook results a re 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 experime nts and that the added noise created by having participants in different se ttings using different computers is easily compensated for by the sample si zes achievable with Web delivery.