Factors Limiting Performance in a Multitone Intensity-Discrimination Task: Disentangling Non-Optimal Decision Weights and Increased Internal Noise
Factors Limiting Performance in a Multitone Intensity-Discrimination Task: Disentangling Non-Optimal Decision Weights and Increased Internal Noise
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DOI：
10.1371/journal.pone.0079830
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发表时间：
2013-11-20
期刊：
影响因子：
3.7
通讯作者：
Jesteadt, Walt
中科院分区：
文献类型：
--
作者：
Oberfeld, Daniel;Kuta, Martha;Jesteadt, Walt
为了确定因素限制性能的多音强度的歧视，我们提出了五个纯音之间交替的响亮（85分贝SPL）和软（30，55，或80分贝SPL）的水平序列。在“整体强度任务”中，听众检测到所有五个音调的水平增加。在“掩蔽任务”中，水平增量仅施加在柔和的音调上，使得柔和的音调目标和大声的音调任务无关的掩蔽者。决策权重量化的重要性，五个音调水平的决定，估计使用分子心理物理学的方法。与以前的研究相一致，在整体强度条件下，听者对响亮的音调比对柔和的音调给予更高的权重。在掩蔽任务中，决策系统地受到被忽略的响亮音调（掩蔽者）的影响。使用最大似然技术，我们估计的内部噪声方差和测试是否内部噪声是更高的交替水平的五音序列比序列中只提出软或只响亮的音调。对于整体强度的任务，我们没有发现增加内部噪音的证据，但听众应用次优决策权重。这些结果是兼容的假设，即存在的响亮的音调不损害的精度表示的强度的软色调在决策阶段，但该信息是不使用在一个最佳的方式，由于在出席软色调的困难。对于掩蔽任务，在某些情况下，我们的数据表明内部噪声增加。此外，听众应用次优决策权重。我们开发的最大似然分析也应该对其他任务或其他感官模式有用。
To identify factors limiting performance in multitone intensity discrimination, we presented sequences of five pure tones alternating in level between loud (85 dB SPL) and soft (30, 55, or 80 dB SPL). In the "overall-intensity task", listeners detected a level increment on all of the five tones. In the "masking task", the level increment was imposed only on the soft tones, rendering the soft tones targets and loud tones task-irrelevant maskers. Decision weights quantifying the importance of the five tone levels for the decision were estimated using methods of molecular psychophysics. Compatible with previous studies, listeners placed higher weights on the loud tones than on the soft tones in the overall-intensity condition. In the masking task, the decisions were systematically influenced by the to-be-ignored loud tones (maskers). Using a maximum-likelihood technique, we estimated the internal noise variance and tested whether the internal noise was higher in the alternating-level five-tone sequences than in sequences presenting only the soft or only the loud tones. For the overall-intensity task, we found no evidence for increased internal noise, but listeners applied suboptimal decision weights. These results are compatible with the hypothesis that the presence of the loud tones does not impair the precision of the representation of the intensity of the soft tones available at the decision stage, but that this information is not used in an optimal fashion due to a difficulty in attending to the soft tones. For the masking task, in some cases our data indicated an increase in internal noise. Additionally, listeners applied suboptimal decision weights. The maximum-likelihood analyses we developed should also be useful for other tasks or other sensory modalities.