Speech-Enhanced and Context Dependent Alerts: Future Implications for Spacecraft Design Abstract

In the future, NASA missions will involve many different space vehicles, habitats, and surface
assets working together to provide safe and productive living and working environments for crew.
Because these systems will be provided by multiple commercial companies working with NASA, it will
be very different from missions of the past, bringing new challenges. One of the challenges is related to
whether NASA should move beyond simple tone annunciation alerting systems, to more advanced
systems that include speech. The other is related to determining the level of consistency required of
safety-critical alert systems across spacecraft. Two studies were completed to address these important
issues. The first study investigated the advantages and disadvantages of a tone+speech alert relative to the
traditional tone-only alert. Results indicate that speech-enhanced alerts initially take longer to silence (the
default action to which NASA personnel are trained), due to the need to listen to the entire message, but
ultimately provided for faster understanding of the alert situation. Speech-enhanced alerts were also
preferred by a large majority of crew-like study participants. An unexpected finding from this first study
was that participants took longer to respond to tone-only alerts when they were mixed with speech-
enhanced alerts. Participants waited to hear the speech message even for alerts they were trained to know
did not contain speech components. This performance error is believed to be due to negative transfer of
training. A second study focused on task and alert performance using a common set of tones across two
contexts (“vehicles”) versus performance with a different set of tones for each context (“vehicle”).
Participants were able to manage two different alert sets successfully; results indicate that discriminability
of the two alert sets played a major role in their success. Implications for the design of spacecraft alerts
are discussed and future areas of research are identified.