Brooks Cassandra J, Anderson Andrew J, Roach Neil W, McGraw Paul V, McKendrick Allison M
J Vis. 2015;15(16):2. doi: 10.1167/15.16.2.
We investigated how aging affects the integration of temporal rate for auditory flutter (amplitude modulation) presented with visual flicker. Since older adults were poorer at detecting auditory amplitude modulation, modulation depth was individually adjusted so that temporal rate was equally discriminable for 10 Hz flutter and flicker, thereby balancing the reliability of rate information available to each sensory modality. With age-related sensory differences normalized in this way, rate asynchrony skewed both auditory and visual rate judgments to the same extent in younger and older adults. Therefore, reliability-based weighting of temporal rate is preserved in older adults. Concurrent presentation of synchronous 10 Hz flicker and flutter improved temporal rate discrimination consistent with statistically optimal integration in younger but not older adults. In a control experiment, younger adults were presented with the same physical auditory stimulus as older adults. This time, rate asynchrony skewed perceived rate with greater auditory weighting rather than balanced integration. Taken together, our results indicate that integration of discrepant auditory and visual rates is not altered due to the healthy aging process once sensory deficits are accounted for, but that aging does abolish the minor improvement in discrimination performance seen in younger observers when concordant rates are integrated.
我们研究了衰老如何影响与视觉闪烁同时呈现的听觉颤动（调幅）的时间频率整合。由于老年人在检测听觉调幅方面表现较差，因此对调幅深度进行了个体调整，以使10 Hz颤动和闪烁的时间频率具有同等的可辨别性，从而平衡每个感觉通道可用的频率信息的可靠性。通过这种方式使与年龄相关的感觉差异正常化后，频率异步在年轻人和老年人中使听觉和视觉频率判断产生同等程度的偏差。因此，老年人中基于可靠性的时间频率加权得以保留。同时呈现同步的10 Hz闪烁和颤动可改善时间频率辨别能力，这与年轻人而非老年人中统计上最优的整合一致。在一个对照实验中，向年轻人呈现与老年人相同的物理听觉刺激。这一次，频率异步以更大的听觉加权使感知频率产生偏差，而非平衡整合。综合来看，我们的结果表明，一旦考虑到感觉缺陷，健康衰老过程不会改变不一致的听觉和视觉频率的整合，但衰老确实消除了年轻观察者在整合一致频率时所看到的辨别性能的轻微改善。
