The task of deciding how long sensory events seem to last is one that the human nervous system appears to perform rapidly and, for sub-second intervals, seemingly without conscious effort. That these estimates can be performed within and between multiple sensory and motor domains suggest time perception forms one of the core, fundamental processes of our perception of the world around us. Given this significance, the current paucity in our understanding of how this process operates is surprising. One candidate mechanism for duration perception posits that duration may be mediated via a system of duration-selective ‘channels’, which are differentially activated depending on the match between afferent duration information and the channels' ‘preferred’ duration. However, this model awaits experimental validation. In the current study, we use the technique of sensory adaptation, and we present data that are well described by banks of duration channels that are limited in their bandwidth, sensory-specific, and appear to operate at a relatively early stage of visual and auditory sensory processing. Our results suggest that many of the computational principles the nervous system applies to coding visual spatial and auditory spectral information are common to its processing of temporal extent.

Perceived time is inherently malleable. For example, adaptation to relatively long or short sensory events leads to a repulsive aftereffect such that subsequent events appear to be contracted or expanded (duration adaptation). Perceived visual duration can also be distorted via concurrent presentation of discrepant auditory durations (multisensory integration). The neural loci of both distortions remain unknown. In the current study we use a psychophysical approach to establish their relative positioning within the sensory processing hierarchy. We show that audiovisual integration induces marked distortions of perceived visual duration. We proceed to use these distorted durations as visual adapting stimuli yet find subsequent visual duration aftereffects to be consistent with physical rather than perceived visual duration. Conversely, the concurrent presentation of adapted auditory durations with nonadapted visual durations results in multisensory integration patterns consistent with perceived, rather than physical, auditory duration. These results demonstrate that recent sensory history modifies human duration perception prior to the combination of temporal information across sensory modalities and provides support for adaptation mechanisms mediated by duration selective neurons situated in early areas of the visual and auditory nervous system (Aubie, Sayegh, & Faure, 2012; Duysens, Schaafsma, & Orban, 1996; Leary, Edwards, & Rose, 2008).

Changes to foot clearance parameters as a result of highlighter presence and position suggest that stairs with high-contrast edge highlighters positioned flush with the tread edge will improve safety on stairs, particularly for those with age-related visual impairment.

PurposeA recent randomised controlled trial indicated that providing long‐term multifocal wearers with a pair of distance single‐vision spectacles for use outside the home reduced falls risk in active older people. However, it also found that participants disliked continually switching between using two pairs of glasses and adherence to the intervention was poor. In this study we determined whether intermediate addition multifocals (which could be worn most of the time inside and outside the home and thus avoid continual switching) could provide similar gait safety on stairs to distance single vision spectacles whilst also providing adequate ‘short‐term’ reading and near vision.MethodsFourteen healthy long‐term multifocal wearers completed stair ascent and descent trials over a 3‐step staircase wearing intermediate and full addition bifocals and progression‐addition lenses (PALs) and single‐vision distance spectacles. Gait safety/caution was assessed using foot clearance measurements (toe on ascent, heel on descent) over the step edges and ascent and descent duration. Binocular near visual acuity, critical print size and reading speed were measured using Bailey‐Lovie near charts and MNRead charts at 40 cm.ResultsGait safety/caution measures were worse with full addition bifocals and PALs compared to intermediate bifocals and PALs. The intermediate PALs provided similar gait ascent/descent measures to those with distance single‐vision spectacles. The intermediate addition PALs also provided good reading ability: Near word acuity and MNRead critical print size were better with the intermediate addition PALs than with the single‐vision lenses (p < 0.0001), with a mean near visual acuity of 0.24 ± 0.13 logMAR (~N5.5) which is satisfactory for most near vision tasks when performed for a short period of time.ConclusionsThe better ability to ‘spot read’ with the intermediate addition PALs compared to single‐vision spectacles suggests that elderly individuals might better comply with the use of intermediate addition PALs outside the home. A lack of difference in gait parameters for the intermediate addition PALs compared to distance single‐vision spectacles suggests they could be usefully used to help prevent falls in older well‐adapted full addition PAL wearers. A randomised controlled trial to investigate the usefulness of intermediate multifocals in preventing falls seems warranted.

Highlights► The perceived duration of visual stimuli varies with spatial frequency content. ► Subjective time expansion in response to oddball stimuli is not a general result. ► Sounds being perceived as longer than visual stimuli is not a general result.