Bowers Jeffrey S
Department of Experimental Psychology, University of Bristol, Bristol, England.
Psychol Rev. 2009 Jan;116(1):220-51. doi: 10.1037/a0014462.
A fundamental claim associated with parallel distributed processing (PDP) theories of cognition is that knowledge is coded in a distributed manner in mind and brain. This approach rejects the claim that knowledge is coded in a localist fashion, with words, objects, and simple concepts (e.g. "dog"), that is, coded with their own dedicated representations. One of the putative advantages of this approach is that the theories are biologically plausible. Indeed, advocates of the PDP approach often highlight the close parallels between distributed representations learned in connectionist models and neural coding in brain and often dismiss localist (grandmother cell) theories as biologically implausible. The author reviews a range a data that strongly challenge this claim and shows that localist models provide a better account of single-cell recording studies. The author also contrast local and alternative distributed coding schemes (sparse and coarse coding) and argues that common rejection of grandmother cell theories in neuroscience is due to a misunderstanding about how localist models behave. The author concludes that the localist representations embedded in theories of perception and cognition are consistent with neuroscience; biology only calls into question the distributed representations often learned in PDP models.
与认知的并行分布式处理（PDP）理论相关的一个基本主张是，知识在心智和大脑中以分布式方式编码。这种方法反对知识以局部主义方式编码的观点，即认为单词、物体和简单概念（如“狗”）是通过其各自专用的表征进行编码的。这种方法的一个假定优势在于这些理论具有生物学合理性。事实上，PDP方法的支持者经常强调在联结主义模型中学习到的分布式表征与大脑中的神经编码之间的紧密相似性，并且常常将局部主义（祖母细胞）理论视为在生物学上不合理而不予考虑。作者回顾了一系列有力挑战这一主张的数据，并表明局部主义模型能更好地解释单细胞记录研究。作者还对比了局部和替代性的分布式编码方案（稀疏编码和粗略编码），并认为神经科学中对祖母细胞理论的普遍摒弃是由于对局部主义模型的运作方式存在误解。作者得出结论，感知和认知理论中所蕴含的局部主义表征与神经科学是一致的；生物学只是对PDP模型中经常学习到的分布式表征提出了质疑。
