Phillips W & Baddeley A (1971) Reaction time and short-term visual memory. Psychonomic Science, 22 (2), pp. 73-74. http://psycnet.apa.org/psycinfo/1972-26338-001
Criticizes M. Posner and S. Keele's (see record 1968-00189-001) method of using differences in RT for physical and name matches to estimate the time constant of visual short-term memory as confounding the decay of the visual trace with the development of a name code. When this confounding is avoided by using stimuli that are hard to name (a 5 * 5 matrix of randomly filled squares), the time constant shown by both RT and errors is consistently longer than that reported by Posner and Keele.
Psychonomic Science: Volume 22, Issue 2