Immediate memory for visually presented verbal material is disrupted by
concurrent speech, even when the speech is unattended and in a foreign
language. Unattended noise does not produce a reliable decrement. These
results have been interpreted in terms of a phonological short-term store that
excludes non-speechlike sounds. The characteristics of this exclusion process
were explored by studying the effects of music on the serial recall of sequences
of nine digits presented visually. Experiment 1 compared the effects of
unattended vocal or instrumental music with quiet and showed that both types
of music disrupted STM performance, with vocal music being more disruptive
than instrumental music. Experiment 2 attempted to replicate this result using
more highly trained subjects. Vocal music caused significantly more disruption
than instrumental music, which was not significantly worse than the silent
control condition. Experiment 3 compared instrumental music with unattended
speech and with noise modulated in amplitude, the degree of modulation being
the same as in speech. The results showed that the noise condition did not differ
from silence; both of these proved less disruptive than instrumental music,
which was in turn less disruptive than the unattended speech condition.
Theoretical interpretation of these results and their potential practical implications
for the disruption of cognitive performance by background music are
discussed.