Dunovan Kyle E, Tremel Joshua J, Wheeler Mark E
Department of Psychology, University of Pittsburgh, PA, USA; Learning Research and Development Center, University of Pittsburgh, PA, USA; Center for the Neural Basis of Cognition, University of Pittsburgh, PA, USA.
Department of Psychology, University of Pittsburgh, PA, USA; Learning Research and Development Center, University of Pittsburgh, PA, USA.
Neuropsychologia. 2014 Aug;61:210-21. doi: 10.1016/j.neuropsychologia.2014.06.024. Epub 2014 Jun 28.
Anticipating a forthcoming sensory experience facilitates perception for expected stimuli but also hinders perception for less likely alternatives. Recent neuroimaging studies suggest that expectation biases arise from feature-level predictions that enhance early sensory representations and facilitate evidence accumulation for contextually probable stimuli while suppressing alternatives. Reasonably then, the extent to which prior knowledge biases subsequent sensory processing should depend on the precision of expectations at the feature level as well as the degree to which expected features match those of an observed stimulus. In the present study we investigated how these two sources of uncertainty modulated pre- and post-stimulus bias mechanisms in the drift-diffusion model during a probabilistic face/house discrimination task. We tested several plausible models of choice bias, concluding that predictive cues led to a bias in both the starting-point and rate of evidence accumulation favoring the more probable stimulus category. We further tested the hypotheses that prior bias in the starting-point was conditional on the feature-level uncertainty of category expectations and that dynamic bias in the drift-rate was modulated by the match between expected and observed stimulus features. Starting-point estimates suggested that subjects formed a constant prior bias in favor of the face category, which exhibits less feature-level variability, that was strengthened or weakened by trial-wise predictive cues. Furthermore, we found that the gain on face/house evidence was increased for stimuli with less ambiguous features and that this relationship was enhanced by valid category expectations. These findings offer new evidence that bridges psychological models of decision-making with recent predictive coding theories of perception.
预期即将到来的感官体验有助于对预期刺激的感知，但也会阻碍对可能性较小的替代刺激的感知。最近的神经影像学研究表明，预期偏差源于特征水平的预测，这种预测增强了早期感官表征，促进了对上下文可能刺激的证据积累，同时抑制了替代刺激。那么合理地说，先验知识对后续感官处理产生偏差的程度应该取决于特征水平预期的精确程度，以及预期特征与观察到的刺激特征的匹配程度。在本研究中，我们调查了在概率性面部/房屋辨别任务中，这两种不确定性来源如何在漂移扩散模型中调节刺激前和刺激后的偏差机制。我们测试了几种合理的选择偏差模型，得出的结论是，预测线索导致了证据积累的起点和速率出现偏差，有利于更可能的刺激类别。我们进一步测试了以下假设：起点的先验偏差取决于类别预期的特征水平不确定性，漂移率的动态偏差由预期和观察到的刺激特征之间的匹配调节。起点估计表明，受试者形成了一种恒定的先验偏差，倾向于面部类别，该类别表现出较小的特征水平变异性，这种偏差会因逐次试验的预测线索而增强或减弱。此外，我们发现，对于特征不那么模糊的刺激，面部/房屋证据的增益增加，并且这种关系会因有效的类别预期而增强。这些发现提供了新的证据，将决策的心理模型与最近的感知预测编码理论联系起来。
