Only the partial-report probe was delayed in this experiment. When masking was
applicable, the masking array was always presented at the immediate offset of the array,
regardless of the delay of the partial-report probe. For this reason, a duration of 100 ms
was used so as to avoid the possibility of a floor effect. Moreover, the interval between
the probe delay and the offset of the stimulus array will be called probe-ISI when
Experiment 2 is discussed. The specific values of the five probe-ISI levels were 0, 150,
250, 500, and 750 ms. Longer probe-ISI values were used here because information in
the iconic store has variously been estimated to last between 250 and 500 ms. When there
was no masking, the condition was analogous to Mewhort et al.'s (1981) Condition 1. The
masking condition in this experiment was not run by Mewhort et al. (1981).
Results
The subjects' intralist and extralist intrusions under the various treatment
combinations are depicted in the left and right middle panels of Figure 2 for comparison
purposes (to Mewhort et al.'s, 1981, study) even though they do not play any role in the
theoretical expectations of this experiment. In the case of intralist intrusions, both the
effects of masking, F(1, 13) = 5.42, and of probe-ISI, F(4, 52) = 5.01, were significant; so
was the interaction between masking and probe-ISI, F(4, 52) = 5.85. In terms of extralist
intrusions, only the main effects of masking, F(1, 13) = 72.45, and of probe-ISI, F(4, 52)
= 5.92, were significant. There was no interaction.
The subjects' partial-report performance as measured in terms of correct recall of
both item identity and its location has been depicted in the top right panel of Figure 4. As
may be seen from the figure, masking reduced performance. Moreover, the subjects'
performance declines as probe-ISI increases in the presence of the mask. The ANOVA
revealed that the main effect of masking was significant, F(1, 13) = 53.38; so was the
main effect of probe-ISI, F(4, 52) = 11.79. The Masking x Probe-ISI interaction was also
significant, F(4, 52) = 5.21.
Masking reduced the availability of item information (see middle panel of Figure
4), but enhanced the availability of location information (bottom panel of Figure 4). The
availability of item information decreased with increases in the probe-ISI of the
partial-report probe. The ANOVA showed that both the main effects of masking and of
probe-ISI were significant; for masking, Fail, 13) = 193.97; for probe-ISI, F(4, 52) =
10.31. The analysis for the availability of location information revealed only a significant
masking effect, F(1, 13) = 12.98.
Discussion
As has been noted, the masking condition used in this experiment was not found
in Mewhort et al.'s (1981) study. In the case of the no-masking condition, the subjects'
extralist and intralist intrusion errors bore a functional relation with probe-ISI similar to