A comparison of simultaneous and sequential brightness judgements

This paper presents the results of brightness matching and brightness discrimination tests carried out using sequential evaluation (temporal juxtaposition) to compare brightness under lamps of different spectral power distribution at mesopic levels of illumination. These data are compared with the results of previous tests, which used simultaneous evaluations (spatial juxtaposition) to enable comparison of these different modes of evaluation. It is concluded that sequential and simultaneous evaluations yield similar estimates of illuminances required for equal spatial brightness and similar levels of precision in this task.