Several studies have suggested that short-term memory is generally improved by chewing gum.
However, we report the first studies to show that chewing gum impairs short-term memory for both
item order and item identity. Experiment 1 showed that chewing gum reduces serial recall of letter
lists. Experiment 2 indicated that chewing does not simply disrupt vocal–articulatory planning required
for order retention: Chewing equally impairs a matched task that required retention of list item identity.
Experiment 3 demonstrated that manual tapping produces a similar pattern of impairment to that of
chewing gum. These results clearly qualify the assertion that chewing gum improves short-term
memory. They also pose a problem for short-term memory theories asserting that forgetting is based
on domain-specific interference given that chewing does not interfere with verbal memory any more
than tapping. It is suggested that tapping and chewing reduce the general capacity to process sequences.