Latency and accuracy of discriminations of odor quality between binary mixtures and their components

Subjects made timed, same-different discriminations of odor quality, with t he following principal findings: (i) latency reflected accuracy, with diffi cult discriminations, i.e. those between 50-50 mixtures and their component s, requiring more time than less difficult discriminations, i.e. those betw een unmixed chemicals. This finding demonstrated the face validity of laten cy as a measure of qualitative similarity. (ii) Latency provided better res olution among pairs of odors than did errors of discrimination. This findin g demonstrated the utility of collecting response times. (iii) Latency-base d similarities among odors tested previously predicted similarities among p airs not yet tested. This finding demonstrated internal/predictive validity . (iv) A signal detection model assuming a differencing strategy best descr ibed the pattern of errors. Subjects appeared to make relative judgements r egarding quality. (v) Finally, latency-based similarities between mixtures and their components demonstrated additivity. This finding suggested that b inary mixtures fall on straight lines connecting their components in 'odor- space'.