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Auditory continuity illusions are perceptual illusions in which receivers perceive an auditory signal as continuous when part of the signal has been removed or obfuscated by a louder noise. Richardson's ground squirrels (Urocitellus richardsonii) communicate alarm acoustically in noisy natural settings. Thus, we tested whether they experience an auditory continuity illusion by presenting free-living squirrels with repeated whistle alarm calls within which every second syllable remained unmanipulated, was partially obfuscated by relatively brief (25 ms) bursts of white noise, or partially obfuscated by longer duration (100 ms) white noise bursts. Field playbacks of alarm calls with brief white noise bursts failed to elicit increased vigilance from receivers relative to unmanipulated calls, whereas calls with longer white noise bursts elicited increased vigilance relative to the other 2 call types. As with previous empirical demonstrations of the auditory continuity illusion in vertebrates, relatively short obfuscating noise resulted in receivers perceiving each syllable as a whole, while longer obfuscating noise caused receivers to perceive the beginning and end of each manipulated syllable as 2 distinct syllables, increasing the perceived syllable repetition rate. These results reveal that Richardson's ground squirrels experience an auditory continuity illusion allowing the extraction of the rate of syllable repetition from conspecific repeated alarm calls in the face of short duration environmental noise. Selection has acted upon receivers to refine the cognitive mechanisms underlying signal perception, facilitating the extraction of information masked by environmental noise. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

In the current study, cross-task interactions between number order and sound intensity judgments were assessed using a dual-task paradigm. Participants first categorized numerical sequences composed of Arabic digits as either ordered (ascending, descending) or non-ordered. Following each number sequence, participants then had to judge the intensity level of a target sound. Experiment 1 emphasized processing the two tasks independently (serial processing), while Experiments 2 and 3 emphasized processing the two tasks simultaneously (parallel processing). Cross-task interference occurred only when the task required parallel processing and was specific to ascending numerical sequences, which led to a higher proportion of louder sound intensity judgments. In Experiment 4 we examined whether this unidirectional interaction was the result of participants misattributing enhanced processing fluency experienced on ascending sequences as indicating a louder target sound. The unidirectional finding could not be entirely attributed to misattributed processing fluency, and may also be connected to experientially derived conceptual associations between ascending number sequences and greater magnitude, consistent with conceptual mapping theory.

The cross-modal impact of number magnitude (i.e. Arabic digits) on perceived sound loudness was examined. Participants compared a target sound's intensity level against a previously heard reference sound (which they judged as quieter or louder ). Paired with each target sound was a task irrelevant Arabic digit that varied in magnitude, being either small (1, 2, 3) or large (7, 8, 9). The degree to which the sound and the digit were synchronized was manipulated, with the digit and sound occurring simultaneously in Experiment 1, and the digit preceding the sound in Experiment 2. Firstly, when target sounds and digits occurred simultaneously, sounds paired with large digits were categorized as loud more frequently than sounds paired with small digits. Secondly, when the events were separated, number magnitude ceased to bias sound intensity judgments. In Experiment 3, the events were still separated, however the participants held the number in short-term memory. In this instance the bias returned. [ABSTRACT FROM AUTHOR]