Ten experiments examined the interactions between vision and audition in stimulusdriven
spatial attention orienting and inhibition of return (IOR). IOR is the demonstration that
subjects are slower to respond to stimuli that are presented at a previously stimulated location. In
each experiment, subjects made go/no-go responses to peripheral targets but not to central
targets. On every trial, a target was preceded by a sensory event, called a "cue," either in the
same modality (intramodal conditions) or in a different modality (crossmodal conditions). The
cue did not predict the location of the target stimulus in any experiment. In some experiments,
the cue and target modalities were fixed and different. Under these conditions, response times to
a visual target were shorter when it appeared at the same location as an auditory cue than when it
appeared on the opposite side of fixation, particularly at short (100 ms) cue-target stimulus onset
asynchronies (Experiments 1A and IB). Similarly, response times to an auditory target were
shorter when it appeared at the same location as a visual cue than when it appeared at a location
on the opposite side of fixation (Experiments 2A and 2B). These crossmodal effects indicate that
stimulus-driven spatial attention orienting might arise from a single supramodal brain
mechanism. IOR was not observed in either crossmodal experiment indicating that it might arise
from modality specific mechanisms. However, for many subjects, IOR did occur between
auditory cues and visual targets (Experiments 3A and 3B) and between visual cues and auditory
targets (Experiment 4A and 4B) when the target could appear in the same modality as the cue on
half of the trials. Finally, the crossmodal effects of stimulus-driven spatial attention orienting on
auditory and visual event-related brain potentials (ERPs) were examined in the final two
experiments. Auditory cues modulated the ERPs to visual targets and visual cues modulated the
ERPs to auditory targets, demonstrating that the mechanisms for spatial attention orienting
cannot be completely modality specific. However, these crossmodal ERP effects were very
different from each other indicating that the mechanisms for spatial attention orienting cannot be
completely shared.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVAU.2429/10165 |
| Date | 05 1900 |
| Creators | MacDonald, John J. |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Relation | UBC Retrospective Theses Digitization Project [http://www.library.ubc.ca/archives/retro_theses/] |
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