Representations pervade our daily experience, from letters representing sounds to bit strings encoding digital files. While such representations require externally defined decoders to convey meaning, conscious experience appears fundamentally different: a neural state corresponding to perceiving a red square cannot alternatively encode the experience of a green square. This intrinsic property of consciousness suggests that conscious representations must be unambiguous in a way that conventional representations are not. We formalize this intuition using information theory, defining representational ambiguity as the conditional entropy H(I|R) over possible interpretations I given a representation R. Through experiments on neural networks trained to classify MNIST digits, we demonstrate that relational structures in network connectivity can unambiguously encode representational content. Using both learned decoders and direct geometric matching, we achieve perfect (100%) accuracy for dropout-trained networks and 38% for standard backpropagation in identifying output neuron class identity, despite identical task performance, demonstrating that representational ambiguity can arise orthogonally to behavioral accuracy. We further show that spatial position information of input neurons can be decoded from network connectivity with R2 up to 0.844. These results provide a quantitative method for measuring representational ambiguity in neural systems and demonstrate that neural networks can exhibit the low-ambiguity representations posited as necessary (though not sufficient) by theoretical accounts of consciousness.
翻译:表征在我们的日常经验中无处不在,从代表声音的字母到编码数字文件的比特串。尽管这类表征需要外部定义的解码器来传递意义,但意识体验似乎存在根本性差异:对应于感知红色方块的神经状态,不能替代性地编码绿色方块的体验。意识的这种内在属性表明,有意识的表征必须具有传统表征所不具备的无歧义特性。我们运用信息论将这一直觉形式化,将表征歧义定义为给定表征R时可能解释I的条件熵H(I|R)。通过对训练用于分类MNIST数字的神经网络进行实验,我们证明网络连接中的关系结构能够无歧义地编码表征内容。通过使用学习解码器和直接几何匹配,我们在识别输出神经元类别身份时,对经过dropout训练的网络实现了完美(100%)准确率,对标准反向传播网络达到38%的准确率——尽管两者任务性能相同,这表明表征歧义可能独立于行为准确度而产生。我们进一步证明,输入神经元空间位置信息可从网络连接中解码,R2值最高达0.844。这些结果为测量神经系统中表征歧义提供了量化方法,并证明神经网络能够展现出理论意识研究提出的低歧义表征——这种表征被视为意识存在的必要条件(虽非充分条件)。