large-capacity finding. This conclusion is counter to the assumption that partial-report
performance is superior because there are more items available in the iconic store than in
the short-term store.
Despite the attractiveness of the display-instruction compatibility hypothesis, the
empirical study in its support is not convincing because the partial-report cue was
presented either before or simultaneously with the partial-report display in Merikle's
(1980) study. This procedural feature violates the "experimental criterion for iconic
memory" recognized by Coltheart (1980, p. 221), who insisted that the partial-report cue
must be presented at or after display offset.
The methodological assumption underlying the partial-report task is that the subjects first
select the relevant subset of items on the basis of a certain dimension before any further
processing is carried out, a process called "select-then-process" (or "selective readout" by
Coltheart, 1980, p. 187). However, the subjects seldom, if ever, have to engage in such
selective readout under so fast a presentation condition. They naturally would treat the
partial-report task as the attention-span task plus some editing before responding when
they are inexperienced in the partial-report task, a strategy called "nonselective readout"
by Coltheart (1980). Seen in this light, the fact that Merikle (1980) has given his subjects
only 12 practice trials on the partial-report task is very unsatisfactory.
Experiment 1 had two objectives: (1) to test Merikle's (1980) interesting
display-instruction compatibility hypothesis when the methodological assumption of the
partial-report task is observed, and (2) to assess the importance of practice on the
partial-report task to the largecapacity finding.
Method
Subjects. Twelve subjects were used in the experiment. All subjects were undergraduate
students at the University of Wollongong. An honorarium was given to the subjects for
participating in the experiment.
Apparatus. A Gerbrands four-channel tachistoscope with a 61159 tachistoscope interface
was used to present the visual materials to the subjects. The tachistoscope was also
connected to a Gerbrands 300 Series timer, an Exact Model 506 sweep function tone
generator, and two automatic card changers. A pair of earphones was used to present the
probe tones.