A sniff in humans typically lasts one to three seconds and is commonly considered to produce a long-exposure shot of the chemical environment that sets the temporal limit of olfactory perception. To break this limit, we devised a sniff-triggered apparatus that controls odorant deliveries within a sniff with a precision of 18 milliseconds. Using this apparatus, we show through rigorous psychophysical testing of 229 participants (649 sessions) that two odorants presented in one order and its reverse become perceptually discriminable when the stimulus onset asynchrony is merely 60 milliseconds (Cohen’s d = 0.48; 95% confidence interval, (55, 59); 120-millisecond difference). Discrimination performance improves with the length of stimulus onset asynchrony and is independent of explicit knowledge of the temporal order of odorants or the relative amount of odorant molecules accumulated in a sniff. Our findings demonstrate that human olfactory perception is sensitive to chemical dynamics within a single sniff and provide behavioural evidence for a temporal code of odour identity.

人类的嗅探通常持续一到三秒，通常被认为会产生化学环境的长时间曝光镜头，从而设定了嗅觉感知的时间极限。为了打破这一限制，我们设计了一种嗅觉触发装置，可以在一次嗅觉中以 18 毫秒的精度控制气味剂的输送。使用该设备，我们通过对 229 名参与者（649 次会话）的严格心理物理测试表明，当刺激开始异步仅为 60 毫秒时，两种以一种顺序呈现的气味剂及其相反的顺序变得在感知上可以区分（Cohen 的 d = 0.48;95% 置信区间，（55,59）;120 毫秒差异）。辨别性能随着刺激开始异步的时间长度而提高，并且与气味剂的时间顺序或嗅觉中积累的气味分子的相对数量的明确知识无关。我们的研究结果表明，人类嗅觉感知对单次嗅觉内的化学动力学很敏感，并为气味身份的时间密码提供了行为证据。