Meta-learned models of cognition make optimal predictions for the actual stimuli presented to participants, but investigating judgment biases by constraining neural networks will be unwieldy. We suggest combining them with cognitive process models, which are more intuitive and explain biases. Rational process models, those that can sequentially sample from the posterior distributions produced by meta-learned models, seem a natural fit.
Convolutional neural networks (CNNs) are often described as promising models of human vision, yet they show many differences from human abilities. We focus on a superhuman capacity of top-performing CNNs, namely, their ability to learn very large datasets of random patterns. We verify that human learning on such tasks is extremely limited, even with few stimuli. We argue that the performance difference is due to CNNs’ overcapacity and introduce biologically inspired mechanisms to constrain it, while retaining the good test set generalisation to structured images as characteristic of CNNs. We investigate the efficacy of adding noise to hidden units’ activations, restricting early convolutional layers with a bottleneck, and using a bounded activation function. Internal noise was the most potent intervention and the only one which, by itself, could reduce random data performance in the tested models to chance levels. We also investigated whether networks with biologically inspired capacity constraints show improved generalisation to out-of-distribution stimuli, however little benefit was observed. Our results suggest that constraining networks with biologically motivated mechanisms paves the way for closer correspondence between network and human performance, but the few manipulations we have tested are only a small step towards that goal.
We describe the MindSet benchmark designed to facilitate the testing of DNNs against controlled experiments reported in psychology. MindSet will focus on a range of low-, middle-, and high-level visual findings that provide important constraints for theory, provide the materials for testing DNNs, and provide an example of how to assess a DNN on each experiment using a ResNet152 pretrained on ImageNet. The goal is not to evaluate how well ResNet152 accounts for human vision, but rather, encourage researchers to assess how well various DNNs account for a range of key human visual phenomena.
On several key issues we agree with the commentators. Perhaps most importantly, everyone seems to agree that psychology has an important role to play in building better models of human vision, and (most) everyone agrees (including us) that deep neural networks (DNNs) will play an important role in modelling human vision going forward. But there are also disagreements about what models are for, how DNN-human correspondences should be evaluated, the value of alternative modelling approaches, and impact of marketing hype in the literature. In our view, these latter issues are contributing to many unjustified claims regarding DNN-human correspondences in vision and other domains of cognition. We explore all these issues in this response.
Abstract Deep neural networks (DNNs) have had extraordinary successes in classifying photographic images of objects and are often described as the best models of biological vision. This conclusion is largely based on three sets of findings: (1) DNNs are more accurate than any other model in classifying images taken from various datasets, (2) DNNs do the best job in predicting the pattern of human errors in classifying objects taken from various behavioral datasets, and (3) DNNs do the best job in predicting brain signals in response to images taken from various brain datasets (e.g., single cell responses or fMRI data). However, these behavioral and brain datasets do not test hypotheses regarding what features are contributing to good predictions and we show that the predictions may be mediated by DNNs that share little overlap with biological vision. More problematically, we show that DNNs account for almost no results from psychological research. This contradicts the common claim that DNNs are good, let alone the best, models of human object recognition. We argue that theorists interested in developing biologically plausible models of human vision need to direct their attention to explaining psychological findings. More generally, theorists need to build models that explain the results of experiments that manipulate independent variables designed to test hypotheses rather than compete on making the best predictions. We conclude by briefly summarizing various promising modeling approaches that focus on psychological data.
Deep neural networks (DNNs) are becoming increasingly popular as a model of the human visual system. However, they show behaviours that are uncharacteristic of humans, including the ability to learn arbitrary data, such as images with pixel values drawn randomly from a Gaussian distribution. We investigated whether this behaviour is due to the learning and memory capacity of DNNs being too high for the training task. We reduced the capacity of DNNs by incorporating biologically motivated constraints – an information bottleneck, internal noise and sigmoid activations – in order to diminish the learning of arbitrary data, without significantly degrading performance on natural images. Internal noise reliably produced the desired behaviour, while a bottleneck had limited impact. Combining all three constraints yielded an even greater reduction in learning capacity. Furthermore, we tested whether these constraints contribute to a network’s ability to generalize by helping it develop more robust internal representations. However, none of the methods could consistently improve generalization.