Venue: NeurIPS 2021 Conference

Reviews:

final_score: rating: 7: Good paper, accept
review_content: summary: Directly inspired by the literature on infant cognition, the authors propose a benchmark to challenge machines' social cognition with a violation of expectation paradigm.
main_review: + This paper is exceptionally well-motivated and tackles one of the most critical topics in developmental psychology from a machine learning perspective. It provides reasonable problem setups.
+ The experiments and protocols are appropriately chosen. The experiments were selected from classic scenarios in developmental psychology. The VOE protocol is also basically the standard in the field.
- Although the experiments replicate the classic studies in developmental, and the questions proposed in the paper are valid, how could the experiments and the study designs prevent the learning system to simply convert this problem into a simple classification problem, therefore may not eventually possess the abilities that the authors hope to give to the machines.
- Of note, this paper was submitted to ICML and almost made it; I was one of the reviewers. The long meta-review commented that all reviewers find the paper interesting but lack proper baseline. In the current revision, the authors did add an additional baseline.
limitations_and_societal_impact: See main review
review_title: null

final_score: rating: 7: Good paper, accept
review_content: summary: EDIT AFTER AUTHOR RESPONSE:  One concern I originally had was whether researchers would actually find this dataset useful, but the review by @Yh1E and @uke7 improved my impression of the utility of the dataset.  I am also pleased that the authors will comment more on the relation of their problem setup to classical MDP and POMDP frameworks.  Hence I am raising my score from 5 to 7.

This paper asks whether AI systems can demonstrate similar theory of mind (ToM) capabilities as human infants.  It identifies a number of key ToM capabilities that have been established in the cognitive science literature, such as learning preferences of observed agents, and predicting that agents will take the most efficient path to their goal.  The paper introduces a benchmark dataset with 2d and 3d videos with simulated agents for the purpose of testing ToM capabilities in AI systems.  Each task in the dataset consists of a familiarization phase with videos intended to allow learning of agent behavior, and then a test phase where the agent exhibits either expected or unexpected behavior.  Taking inspiration from the fact that human babies look longer at unexpected stumli, the paper introduces a "violation of expectations (VoE)" framework for evaluating AI systems.  Under this paradigm, an AI system is considered to demonstrate evidence of human-like learning if it has greater prediction error for video frames in the unexpected condition than in the expected condition for the testing episode.  It evaluates two recent approaches on this dataset, behavior cloning, and offline RL.
main_review: Originality:  High.  The paper takes a very different approach to the problem than comparable recent works in RL.  It doesn't start with any formal theory of how we might model a real-world agent (e.g. POMDP) but rather takes the cognitive science literature as a starting point.  The strong grounding in human cognitive science is a strength of this work.  The cognitive science perspective is also critical for motivating a new paradigm for evaluating artificial agents: testing whether artificial agents experience similar prediction errors to humans when seeing agents demonstrate behavior that is inconsistent with previously observed behavior.  That said, it is not clear the degree to which VOE adds to agent evaluation beyond correct prediction. If an artificial agent has high predictive accuracy, doesn't it also pass the VOE benchmark?  How does VOE add non-redundant information about the ToM capabilities of an artificial agent?

Quality:  Mixed.  For a psychology venue, this would be a great paper.  But relative to the ML literature, the technical sophistication here is lacking.  The paper starts off with the cognitive science literature, which is great, but it does not go further to completely bridge to the formalisms that have been used in the artificial intelligence literature.  The technical contribution of this paper would be elevated if the paper made a serious effort to consider what human learning capabilities say about the kinds of agent models humans are likely to employ.  For instance, is there a particular type of POMDP model that would result in an agent that has stable preferences, which takes instrumental action to reach goals, and which takes the path of least effort to get there?  Another potential contribution that was not addressed by this paper is to think about how formalisms used in AI could be used to better understand infant cognition.  To what extent are infants able to learn to predict general POMDP agents?  The results also cast doubt on the correctness of the evaluation.  In the Shu et al. paper, the BC method was able to achieve above-chance prediction on the goal preference task, so why does it get below-chance performance in the BIB dataset?  How do we know that the BIB dataset has sufficient training data to enable performance comparable to human infants?

Clarity:  The paper is clearly written, although the VOE testing criteria could be emphasized more as it is rather novel.

Significance:  Moderate.  It seems valuable to look at human behavior to motivate benchmarks for AI, but the benchmark introduced here still seems rather limited.  Even if an artificial agent could be developed that would pass all of the tasks in the benchmark, I am not convinced that this would be conclusive evidence for the agent to have strong theory of mind.  The fact that BC and IRL perform poorly could be an important finding, but it depends on the reason for their failure, which has not been conclusively established here.

Other comments:
* Supplemental materials - some videos are mislabeled (expected switched with unexpected).  I could not play some of the videos (e.g. eval-videos-3d/efficient_action_b_expected.mp4).
* Line 322: "characteristics"
limitations_and_societal_impact: The paper does not adequately address the limitations of the benchmark, as there is no attempt to rule out alternative means that artificial agents without ToM capabilities might still be able to pass the BIB benchmarks.  The performance of benchmark methods is surprisingly bad and needs to be explained.  It is not clear that BIB dataset has enough or sufficiently varied training data to allow for generalization.

The paper could be improved by further explanation of the performance of the methods that were evaluated, addressing the adequacy of the amount and diversity of training data, and the paper should also spend some effort attempting to rule out potential alternative explanations for a method to pass the BIB benchmark.  The paper could also discuss the extent to which the VOE paradigm adds to the existing state-of-the-art in evaluating artificial agents, beyond the naturalistic argument of attempting to match human behavior.  After all, one does not have to imitate human behavior to achieve human-level performance, as human-like performance may plausibly emerge as a by-product of trying to optimize a simpler criterion.
review_title: null

final_score: rating: 6: Marginally above the acceptance threshold
review_content: summary: This paper presents the Baby Intuitions Benchmark (BIB) to test deep learning methods abilities’ to reason about how other agents will behave. BIB is inspired by human infants’ expectations about other agents, as clearly laid out in the paper. The authors include several different capabilities/tasks within the benchmark along with their developmental background, testing 3 different models across 5 different tasks. These models only perform well in the simplest of tasks, suggesting that the benchmark tests capabilities that are not trivial to acquire with current methods.
main_review: To summarize my review, I found the paper compelling as a pointer to how rich human social inferences can be, and just how lacking a variety of ML baselines are in this respect. My most critical technical comments relate to including a model that relies on bayesian inference, as motivation for how well models could perform if they had the right kinds of structure in them (as in AGENT [1]). While I am not sure how much this benchmark will be picked up by the general machine learning community, it does point out specific limitations with current methods for social inference, and could therefore be useful especially for researchers in human computer interaction, human robot interaction, and multi-agent ML researchers generally. 

However, I am choosing a low rating because this is not the appropriate track for this paper. This paper does not make a meaningful contribution for the main NeurIPS track, in that it does not show new results either for cognitive science/neuroscience, or provide new algorithms for machine learning methods. It instead tests a variety of existing methods on a new benchmark. It should absolutely be submitted to the “Datasets and Benchmarks” track. If it is possible to move the paper to this other track, my rating would jump to 7 for that track. This alternative track has a deadline for submission of August 27, please see https://neurips.cc/Conferences/2021/CallForDatasetsBenchmarks for details.

For context, I think that for a benchmark to be accepted to the main track, it needs to either (1) provide access to data that would otherwise be difficult for individual researchers to collect, like neural recordings, human annotations, or human experimental data, or (2) clearly address an important ML problem, and provide clear reasons for why the benchmark will be very widely taken up within the ML community. While I like the BIB benchmark, it does not fit into (1), and I am not convinced that it clearly falls into category (2) either (due to similarities to existing benchmarks, as well as BIB’s somewhat bespoke passive setting where agents cannot interact with the environment), which is why I strongly recommend considering the datasets and benchmarks track. 

### Excellent paper layout - very clear writing

The section headings - stating the question of the specific sub-task - and then giving the developmental background and the specifics of the familiarization and test trials, was very clear. My only additional suggestion would be to include a small wrapped figure in each of these sections (like Figures 4, 5, and 6) to help a reader visualize what the task looks like as well. 

### Reasonable ML baselines, although could include bayesian inference agent

The baselines included by the authors, an offline RL, behavioral cloning, and video RNN models, seemed reasonable for the presented task to cover a variety of approaches that ML researchers might try first. The authors explained very well why inverse reinforcement learning approaches are not suitable for this benchmark, precisely because agents do not have access to the underlying environment to attempt to create their own plans. 

My only suggestion would be to include an “aspirational” baseline as in AGENT [1], that uses significantly more structure (in the form of objects and agents), but as a result is able to solve the presented tasks. I think this could help convince readers that the benchmark is interesting, as it pushes on building these more structured representations in order to enable success. Without something like this, researchers might think the benchmark is just too difficult, and not try it. 

### Benchmark's passive nature may prevent widespread adoption

The benchmark's passive nature is a limitation in that most real setups with human-computer interaction, for example, do give agents access to the environment, and this helps dramatically with tasks like goal inference and inverse reinforcement learning. As a result, I think this benchmark as proposed will be slightly less relevant for the wider swath of the NeurIPS community, although it is well motivated in the context of developmental cognitive science.

### Behavioral validation incomplete - do infants really perform at 100% accuracy for these problems?

A lingering question I had throughout looking at the paper was: how well would infants really perform on these tasks? As I understand the developmental literature for these kinds of tasks, it is generally not the case that 100% of infants choose the correct stimulus 100% of the time. Can the authors comment on this? Is there a success percentage less than 100 that would be sufficient to say that a machine learning model has performed at the same level as an infant for some of these different tasks?

### Questions about benchmark size

The authors use a breakdown of 10,000, 10,000, 4000, and 4000 tasks in the “background” training. Can the authors please clarify why they used this particular breakdown?

[1] Shu et al, ICML 2021. AGENT: A Benchmark for Core Psychological Reasoning
limitations_and_societal_impact: I see no obvious limitations/societal impact with the proposed benchmark.
review_title: null

final_score: rating: 6: Marginally above the acceptance threshold
review_content: summary: 
The paper starts from developmental studies on infants that showcase that infants have ways of ascribing certain types of intentionalities in what they observe, and proposes a benchmark dataset to evaluate whether modern AI/ML techniques are capable of the same type of reasoning. The paper presents a list of scenarios that demonstrate varying forms of intentionality, and also evaluates certain baseline AI/ML techniques on the benchmark scenarios to demonstrate the insufficiency of the baseline. 
main_review: I will start with my conclusion:  

Would I use the benchmark if it were available? Yes, in some form or another. At the very least as inspiration to develop new techniques within my area of interest, even if this might be different from what the authors have in mind (which seems to be deep learning over videos)

Is the paper "scientifically" optimal? No, neither in terms of presentation/motivation, nor in terms of convincing that the problem presented would end up with machines that have a notion of intentionality.

The authors mention the existence of another similar dataset recently released (which I did not check). I would expect a more elaborate discussion (not confined to a single paragraph) of the commonalities and differences.

Although I understand the underlying reason of why deep learning models are "expected" to fail the BIB tests, I am not sure whether a theory of "object preference" is needed for machines to do well in these tests. What is there to preclude an experimenter from biasing the deep learning in a manner that gives preferences to objects rather than location? Is there even a meaningful way to evaluate whether a deep learning architecture learns infant-like preferences, or ends up finding "shortcuts" to these tasks?

Since not all 8 familiarization instances are shown, it is hard to know what expectations one is expected to form in some of the presented scenarios. For example in the scenario of section 2.3, what in the familiarization instances should lead one to the expectation that if the preferred object is inaccessible, then reach for the other object? Shouldn't at least one such case be in the training data? Or are the two test instances shown simultaneously, and it is a matter of relative preference between the two?

I didn't quite understand the material offered. Is it several thousand (instead of 8) familiarization instances, and then several (instead of 1-2) test instances? Or is it several thousand episodes each comprising 8 familiarization instances and 1-2 test instances? In the latter case, is this really replicating the infant scenarios? I would say no, since the ML is learning also from the test instances (within the training episodes). This is clearly okay (since the evaluation episodes are not used), but it seems to change the setting from that in the infant developmental studies.

It is also unclear whether the trials (within each episode) show actual movement or just arrows indicating the movement. Figure 7 suggests the former, but up to this point in the paper the latter seems to be implied.

Some of my questions above are addressed in the appendix, but perhaps not so clearly in the main text. I think there is room to clarify things in the main text as well. I would propose that one of the scenarios (e.g., preference for target object over target location) is used throughout to demonstrate in more detail all the concepts, and then the rest of the scenarios can be presented at a higher-level. Also, section 3 seems to come rather late in the narrative. Perhaps the paper presented from the point of view of ML rather than developmental psychology would offer a more compelling narrative, given the target conference?

I am not sure if the 2D and 3D videos are necessary. Why not simply offer a symbolic representation (what you have in the JSON files) as the input?

limitations_and_societal_impact: Seems fine.
review_title: null

Meta-review: This paper introduces a new benchmark set for visual cognition tasks, inspired by looking-time experiments done with human babies. I think this work would be useful even if the only role were to highlight the questions and methodologies used by developmental psychology to student non-verbal intelligence, but care was taken to provide a broad benchmark that I think will provoke interesting ML work. The reviewers generally agree, though note a few requests for clarification and context.

(Note, it's probably the case that this paper fits better into the D&B track, but since that track is brand new this year I don't think the authors should be penalized for choosing the main track.)
Decision: Accept (Poster)