Exploring the properties of alarm signals that makes them attention-capturing: The Role of interstimulus intervals

Abstract: Alarm signals such as sirens are crucial in alerting users of impending dangers. Therefore, it is important that the siren is designed so it can capture user's attention. In a previous study (Hansson, 2017) background alarm sirens composed of changing-state sounds with an embedded temporal deviant, produced greater disruption of serial short-term memory than a signal without a temporal deviant. However, to give rise to disruption the siren needed to change from fast to slow, since a change from slow to fast was impotent in its effect on task performance. This was further addressed in Hansson (2018) where it was shown that acoustic change appeared to be a necessary prerequisite for obtaining the fast-to-slow temporal deviant effect: When steady-state sounds were used fast-to-slow and or slow-to-fast temporal deviants were equally disruptive of serial recall. However, in order to create a steady-state siren, inter-stimulus intervals were incorporated into the siren to prevent the continuous uninterrupted presentation of a single tone. Since inter-stimulus intervals were not used in Hansson (2017) it could be the presence of these that eliminated the potency of the fast-to-slow over the slow-to-fast temporal deviation effect in Hansson (2018). Therefore, the current study was undertaken to investigate whether the embedding inter-stimulus intervals within a changing-state siren would restore the potency of the fast-to-slow temporal deviation over the slow-to-fast temporal deviation in capturing attention. The additional disruption for fast-to-slow temporal deviants over slow-to-fast temporal deviants (that did not produce disruption relative to control) returned in the current study when inter-stimulus intervals were included within the siren. The results support the notion that the additional disruption produced by fast-to-slow, over slow-to-fast temporal deviants depend on the changing-state properties of the siren. Implications of this result for the design and operation of sirens within ecologically valid settings are discussed.