Lutfi Robert A, Jesteadt Walt
Department of Communicative Disorders and Waisman Center University of Wisconsin, Madison, Wisconsin 53706, USA.
J Acoust Soc Am. 2006 Dec;120(6):3853-60. doi: 10.1121/1.2361184.
Molecular psychophysics attempts to model the observer's response to stimuli as they vary from trial to trial. The approach has gained popularity in multitone pattern discrimination studies as a means of estimating the relative reliance or decision weight listeners give to different tones in the pattern. Various factors affecting decision weights have been examined, but one largely ignored is the relative level of tones in the pattern. In the present study listeners detected a level-increment in a sequence of 5, 100-ms, 2.0-kHz tone bursts alternating in level between 40 and 80 dB SPL. The level increment was made largest on the 40-dB tones, yet despite this all four highly-practiced listeners gave near exclusive weight to the 80-dB tones. The effect was the same when the tones were replaced by bursts of broadband Gaussian noise alternating in level. It was reduced only when the level differences were made <10 dB, and it was entirely reversed only when the low-level tones alternated with louder bursts of Gaussian noise. The results are discussed in terms of the effects of both sensory and perceptual factors on estimates of decision weights.
分子心理物理学试图对观察者在每次试验中对不同刺激的反应进行建模。这种方法在多音模式辨别研究中越来越受欢迎，它可以用来估计听众在模式中对不同音调的相对依赖程度或决策权重。人们已经研究了影响决策权重的各种因素，但其中一个很大程度上被忽视的因素是模式中音调的相对水平。在本研究中，听众检测到一系列5个、持续100毫秒、频率为2.0千赫的纯音脉冲串的电平增量，这些脉冲串的声压级在40到80分贝声压级之间交替变化。电平增量在40分贝的音调上最大，但尽管如此，所有四位训练有素的听众几乎都只看重80分贝的音调。当用宽带高斯噪声脉冲串代替音调，且噪声电平交替变化时，效果相同。只有当电平差小于10分贝时，这种效果才会减弱，只有当低电平音调与更大声的高斯噪声脉冲串交替时，这种效果才会完全逆转。我们将根据感觉和知觉因素对决策权重估计的影响来讨论这些结果。
