In plain words: They examined what self-supervised training actually does to a network's internal representations across many models and settings. The training objective's built-in penalty pulls samples with the same true label into tight groups, more than random groupings, which improves classification while squeezing out extra information.
Abstract
Self-supervised learning (SSL) is a powerful tool in machine learning, but understanding the learned representations and their underlying mechanisms remains a challenge. This paper presents an in-depth empirical analysis of SSL-trained representations, encompassing diverse models, architectures, and hyperparameters. Our study reveals an intriguing aspect of the SSL training process: it inherently facilitates the clustering of samples with respect to semantic labels, which is surprisingly driven by the SSL objective's regularization term. This clustering process not only enhances downstream classification but also compresses the data information. Furthermore, we establish that SSL-trained representations align more closely with semantic classes rather than random classes. Remarkably, we show that learned representations align with semantic classes across various hierarchical levels, and this alignment increases during training and when moving deeper into the network. Our findings provide valuable insights into SSL's representation learning mechanisms and their impact on performance across different sets of classes.
Ido Ben-Shaul, Ravid Shwartz-Ziv, Tomer Galanti, Shai Dekel, Yann LeCun
arXiv:2305.15614 · cs.LG, cs.AI · submitted May 24, 2023 · updated May 31, 2023
abstract · pdf · html
If i've understood the question of the paper correctly, my answer is simple: we induce "semantic categorisation" into (non-semantic) data structure.
In otherwords: we do not take random pictures of dogs (eg., at a zoom of 1000x on their skin); we make them subjects of photographs (and so on).
We exploit non-random non-semantic structure in communication as a kind of "helpful meta-data".
In ML the answer is always just "the data generating process (us) gave the data those properties" -- I struggle to see why so few people in the space fail to mention this
I think it's highly doubtful anything in ML (, modern AI) would work if pointed "open-camera" at arbitary parts of the world. The trick is always: we hold the camera.