Temporal judgments depend both on the regularity of event sequences and on the sensory modality through which events are delivered. The authors set out to determine whether modality-specific sequence history and across-trial modality context make separate contributions to two components of temporal perception in isochrony judgments: temporal sensitivity and perceived timing. The study focuses on isochronous sequences and contrasts unimodal (all events same modality) with crossmodal (final event switches modality) endings.
Participants completed an isochrony judgment task in which each trial contained six events. The first five events formed an isochronous train delivered either in the auditory or visual modality. The sixth event could either match the established modality (a modality-consistent ending) or switch to the other modality (a modality-inconsistent ending), resulting in four sequence types.
Across-trial context was manipulated with a presentation mode factor: sequence types were either presented in separate blocks or randomly interleaved across trials. This presentation mode manipulation was between participants and was confounded with hardware settings; because of this confound, effects involving presentation mode were treated by the authors as descriptive rather than definitive.
Participants judged whether the sixth event occurred earlier or later than expected based on the preceding isochronous sequence. The analysis derived two standard psychophysical indices from these judgments: the just noticeable difference (JND) as a measure of temporal sensitivity and the point of subjective equality (PSE) as a measure of perceived timing.
The study used the JND to index how precisely participants could discriminate deviations from isochrony — lower JNDs indicate better temporal sensitivity. The PSE captured systematic shifts in perceived timing, indicating biases whereby an event must be earlier or later than veridical to be perceived as matching the expected timing.
Temporal sensitivity differed by sensory modality and by whether the final event matched the modality history. Specifically, the JNDs were better (indicating more precise temporal sensitivity) for auditory sequences than for visual sequences. Additionally, sequences with modality-consistent endings produced better JNDs than sequences with modality-inconsistent endings. These results indicate that both the sensory modality of the sequence and the modality-consistency of the ending influence how precisely timing deviations are detected.
Because presentation mode was between participants and confounded with hardware, effects that involved presentation mode were reported descriptively and not emphasized as conclusive in the primary interpretation.
Perceived timing, as indexed by the PSE, showed different patterns from temporal sensitivity. The authors report large shifts in PSEs for modality-switch (modality-inconsistent) endings in the interleaved presentation group. This indicates that when different sequence types are randomly interleaved across trials, switching the modality of the final event produced substantial context-dependent biases in perceived timing.
These PSE shifts for modality-switch endings contrasted with the JND pattern, which related to modality and sequence consistency. The dissociation suggests that sensitivity to timing deviations and the subjective centering of perceived timing can be driven by distinct factors.
The combined results support a functional separation between sequence-related effects on temporal sensitivity (measured by JND) and context-dependent biases in perceived timing (measured by PSE). In this study, modality history and modality-consistency primarily affected temporal sensitivity, while across-trial modality context (notably when trials were interleaved) produced large shifts in perceived timing for modality-switch endings.
Overall, the findings highlight that both modality-specific sequence history and broader trial context shape temporal perception, but they do so in different ways: one influencing discrimination precision, the other producing systematic timing biases.
The study was approved by the Science, Technology, Engineering and Mathematics Ethical Review Committee of the University of Birmingham (ERN_11-1241) and complied with the Declaration of Helsinki. Informed consent was obtained from all participants. The authors declared no competing interests.
Relevant study metadata: Min Susan Li and Massimiliano Di Luca. Exp Brain Res. 2026 Aug 6;244(9):173. PMID: 42560522. DOI: 10.1007/s00221-026-07371-1. Grants/funding noted in the record include EP/V034987/1 (EPSRC) and 304235/FP7 People: Marie-Curie Actions (European Union). Keywords listed by the source include crossmodal timing, isochrony, modality expectation, perceptual timing, and temporal sensitivity.