Previous studies have shown that behavioral responses to auditory, visual,
and tactile stimuli are modulated by expectancies regarding the likely moda
lity of an upcoming stimulus (see Spence & Driver, 1997). In the present st
udy, we investigated whether people can also selectively attend to the chem
osensory modality (involving responses to olfactory, chemical, and painful
stimuli). Participants made speeded spatial discrimination responses (left
vs. right) to an unpredictable sequence of odor and tactile targets. Odor s
timuli were presented to either the left or the right nostril, embedded in
a birhinally applied constant airstream. Tactile stimuli were presented to
the left or the right hand. On each trial, a symbolic visual cue predicted
the likely modality for the upcoming target (the cue was a valid predictor
of the target modality on the majority of trials). Response latencies were
faster when targets were presented in the expected modality than when they
were presented in the unexpected modality, showing for the first time that
behavioral responses to chemosensory stimuli can be modulated by selective
attention.