Department of Psychology and Neurosciences Graduate Program, University of California, San Diego, La Jolla, California 92093, USA.
J Neurosci. 2012 Jun 6;32(23):7992-8003. doi: 10.1523/JNEUROSCI.0340-12.2012.
When people make decisions quickly, accuracy suffers. Traditionally, speed-accuracy tradeoffs (SATs) have been almost exclusively ascribed to changes in the amount of sensory evidence required to support a response ("response caution") and the neural correlates associated with the later stages of decision making (e.g., motor response generation and execution). Here, we investigated whether performance decrements under speed pressure also reflect suboptimal information processing in early sensory areas such as primary visual cortex (V1). Human subjects performed an orientation discrimination task while emphasizing either response speed or accuracy. A model of choice behavior revealed that the rate of sensory evidence accumulation was selectively modulated when subjects emphasized accuracy, but not speed, suggesting that changes in sensory processing also influence the SAT. We then used fMRI and a forward encoding model to derive orientation-selective tuning functions based on activation patterns in V1. When accuracy was emphasized, the extent to which orientation-selective tuning profiles exhibited a theoretically optimal gain pattern predicted both response accuracy and the rate of sensory evidence accumulation. However, these relationships were not observed when subjects emphasized speed. Collectively, our findings suggest that, in addition to lowered response thresholds, the performance decrements observed during speeded decision making may result from a failure to optimally process sensory signals.
当人们快速做出决策时，准确性会受到影响。传统上，速度准确性权衡（SAT）几乎完全归因于支持响应所需的感官证据量的变化（“响应谨慎”）和与决策后期相关的神经相关性（例如，运动响应生成和执行）。在这里，我们研究了在速度压力下表现下降是否也反映了早期感官区域（例如初级视觉皮层（V1））中的信息处理不当。人类受试者在强调响应速度或准确性的情况下执行方向辨别任务。选择行为的模型表明，当受试者强调准确性而不是速度时，感官证据积累的速度会选择性地调节，这表明感官处理的变化也会影响 SAT。然后，我们使用 fMRI 和前向编码模型根据 V1 中的激活模式推导出方向选择性调谐函数。当强调准确性时，方向选择性调谐曲线呈现理论上最佳增益模式的程度可以预测响应准确性和感官证据积累的速度。但是，当受试者强调速度时，没有观察到这些关系。总的来说，我们的发现表明，在快速决策过程中观察到的性能下降除了降低响应阈值外，还可能是由于未能最佳处理感官信号。
