Barbaro Ludwig, Peelen Marius V, Hickey Clayton
Center for Mind/Brain Sciences, University of Trento, 38068, Rovereto, Italy.
Center for Mind/Brain Sciences, University of Trento, 38068, Rovereto, Italy
J Neurosci. 2017 Oct 25;37(43):10438-10450. doi: 10.1523/JNEUROSCI.1128-17.2017. Epub 2017 Sep 26.
Objects associated with reward draw attention and evoke enhanced activity in visual cortex. What is the underlying mechanism? One possibility is that reward's impact on vision is mediated by unique circuitry that modulates sensory processing, selectively increasing the salience of reward-associated stimuli. Alternatively, effects of reward may be part of a more general mechanism that prioritizes the processing of any beneficial object, importantly including stimuli that are associated with the evasion of loss. Here, we test these competing hypotheses by having male and female humans detect naturalistic objects associated with monetary reward, the evasion of equivalent loss, or neither of these. If vision is economically normative, processing of objects associated with reward and evasion of loss should be prioritized relative to neutral stimuli. Results from fMRI and behavioral experiments show that this is not the case: whereas objects associated with reward were better detected and represented in ventral visual cortex, detection and representation of stimuli associated with the evasion of loss were degraded. Representations in parietal cortex reveal a notable exception to this pattern, showing enhanced encoding of both reward- and loss-associated stimuli. Experience-driven visual prioritization can thus be economically irrational, driven by valence rather than objective utility. Normative economic models propose that gain should have the same value as evasion of equivalent loss. Is human vision rational in this way? Objects associated with reward draw attention and are well represented in visual cortex. This is thought to have evolutionary origins, highlighting objects likely to provide benefit in the future. But benefit can be conferred not only through gain, but also through evasion of loss. Here we demonstrate that the visual system prioritizes real-world objects presented in images of natural scenes only when these objects have been associated with reward, not when they have provided the opportunity to evade financial loss. Visual selection is thus non-normative and economically irrational, driven by valence rather than objective utility.
与奖励相关的物体能够吸引注意力，并在视觉皮层中引发增强的活动。其潜在机制是什么？一种可能性是，奖励对视觉的影响是由独特的神经回路介导的，该回路调节感觉处理，选择性地增加与奖励相关刺激的显著性。另一种可能性是，奖励的作用可能是一种更普遍机制的一部分，该机制优先处理任何有益物体，重要的是包括与避免损失相关的刺激。在这里，我们通过让男性和女性检测与金钱奖励、避免同等损失或两者都无关的自然物体，来检验这些相互竞争的假设。如果视觉在经济上是规范的，那么与奖励和避免损失相关的物体的处理相对于中性刺激应该被优先考虑。功能磁共振成像（fMRI）和行为实验的结果表明情况并非如此：虽然与奖励相关的物体在腹侧视觉皮层中能被更好地检测和表征，但与避免损失相关的刺激的检测和表征却有所退化。顶叶皮层的表征显示了这种模式的一个显著例外，即对与奖励和损失相关的刺激都有增强的编码。因此，经验驱动的视觉优先选择在经济上可能是不理性的，是由效价而非客观效用驱动的。规范的经济模型提出，收益应该与避免同等损失具有相同的价值。人类的视觉在这方面是理性的吗？与奖励相关的物体能够吸引注意力，并在视觉皮层中得到很好的表征。这被认为有进化起源，突出了未来可能带来益处的物体。但益处不仅可以通过收益来赋予，也可以通过避免损失来实现。在这里，我们证明，只有当自然场景图像中呈现的真实物体与奖励相关时，视觉系统才会对其进行优先选择，而当这些物体提供了避免经济损失的机会时则不会。因此，视觉选择是非规范的，在经济上是不理性的，是由效价而非客观效用驱动的。
