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Welbl, Johannes
Consensus, dissensus and synergy between clinicians and specialist foundation models in radiology report generation
Tanno, Ryutaro, Barrett, David G. T., Sellergren, Andrew, Ghaisas, Sumedh, Dathathri, Sumanth, See, Abigail, Welbl, Johannes, Singhal, Karan, Azizi, Shekoofeh, Tu, Tao, Schaekermann, Mike, May, Rhys, Lee, Roy, Man, SiWai, Ahmed, Zahra, Mahdavi, Sara, Matias, Yossi, Barral, Joelle, Eslami, Ali, Belgrave, Danielle, Natarajan, Vivek, Shetty, Shravya, Kohli, Pushmeet, Huang, Po-Sen, Karthikesalingam, Alan, Ktena, Ira
Radiology reports are an instrumental part of modern medicine, informing key clinical decisions such as diagnosis and treatment. The worldwide shortage of radiologists, however, restricts access to expert care and imposes heavy workloads, contributing to avoidable errors and delays in report delivery. While recent progress in automated report generation with vision-language models offer clear potential in ameliorating the situation, the path to real-world adoption has been stymied by the challenge of evaluating the clinical quality of AI-generated reports. In this study, we build a state-of-the-art report generation system for chest radiographs, $\textit{Flamingo-CXR}$, by fine-tuning a well-known vision-language foundation model on radiology data. To evaluate the quality of the AI-generated reports, a group of 16 certified radiologists provide detailed evaluations of AI-generated and human written reports for chest X-rays from an intensive care setting in the United States and an inpatient setting in India. At least one radiologist (out of two per case) preferred the AI report to the ground truth report in over 60$\%$ of cases for both datasets. Amongst the subset of AI-generated reports that contain errors, the most frequently cited reasons were related to the location and finding, whereas for human written reports, most mistakes were related to severity and finding. This disparity suggested potential complementarity between our AI system and human experts, prompting us to develop an assistive scenario in which Flamingo-CXR generates a first-draft report, which is subsequently revised by a clinician. This is the first demonstration of clinician-AI collaboration for report writing, and the resultant reports are assessed to be equivalent or preferred by at least one radiologist to reports written by experts alone in 80$\%$ of in-patient cases and 60$\%$ of intensive care cases.
Training Compute-Optimal Large Language Models
Hoffmann, Jordan, Borgeaud, Sebastian, Mensch, Arthur, Buchatskaya, Elena, Cai, Trevor, Rutherford, Eliza, Casas, Diego de Las, Hendricks, Lisa Anne, Welbl, Johannes, Clark, Aidan, Hennigan, Tom, Noland, Eric, Millican, Katie, Driessche, George van den, Damoc, Bogdan, Guy, Aurelia, Osindero, Simon, Simonyan, Karen, Elsen, Erich, Rae, Jack W., Vinyals, Oriol, Sifre, Laurent
We investigate the optimal model size and number of tokens for training a transformer language model under a given compute budget. We find that current large language models are significantly undertrained, a consequence of the recent focus on scaling language models whilst keeping the amount of training data constant. By training over 400 language models ranging from 70 million to over 16 billion parameters on 5 to 500 billion tokens, we find that for compute-optimal training, the model size and the number of training tokens should be scaled equally: for every doubling of model size the number of training tokens should also be doubled. We test this hypothesis by training a predicted compute-optimal model, Chinchilla, that uses the same compute budget as Gopher but with 70B parameters and 4$\times$ more more data. Chinchilla uniformly and significantly outperforms Gopher (280B), GPT-3 (175B), Jurassic-1 (178B), and Megatron-Turing NLG (530B) on a large range of downstream evaluation tasks. This also means that Chinchilla uses substantially less compute for fine-tuning and inference, greatly facilitating downstream usage. As a highlight, Chinchilla reaches a state-of-the-art average accuracy of 67.5% on the MMLU benchmark, greater than a 7% improvement over Gopher.
Competition-Level Code Generation with AlphaCode
Li, Yujia, Choi, David, Chung, Junyoung, Kushman, Nate, Schrittwieser, Julian, Leblond, Rémi, Eccles, Tom, Keeling, James, Gimeno, Felix, Lago, Agustin Dal, Hubert, Thomas, Choy, Peter, d'Autume, Cyprien de Masson, Babuschkin, Igor, Chen, Xinyun, Huang, Po-Sen, Welbl, Johannes, Gowal, Sven, Cherepanov, Alexey, Molloy, James, Mankowitz, Daniel J., Robson, Esme Sutherland, Kohli, Pushmeet, de Freitas, Nando, Kavukcuoglu, Koray, Vinyals, Oriol
Programming is a powerful and ubiquitous problem-solving tool. Developing systems that can assist programmers or even generate programs independently could make programming more productive and accessible, yet so far incorporating innovations in AI has proven challenging. Recent large-scale language models have demonstrated an impressive ability to generate code, and are now able to complete simple programming tasks. However, these models still perform poorly when evaluated on more complex, unseen problems that require problem-solving skills beyond simply translating instructions into code. For example, competitive programming problems which require an understanding of algorithms and complex natural language remain extremely challenging. To address this gap, we introduce AlphaCode, a system for code generation that can create novel solutions to these problems that require deeper reasoning. In simulated evaluations on recent programming competitions on the Codeforces platform, AlphaCode achieved on average a ranking of top 54.3% in competitions with more than 5,000 participants. We found that three key components were critical to achieve good and reliable performance: (1) an extensive and clean competitive programming dataset for training and evaluation, (2) large and efficient-to-sample transformer-based architectures, and (3) large-scale model sampling to explore the search space, followed by filtering based on program behavior to a small set of submissions.
Scaling Language Models: Methods, Analysis & Insights from Training Gopher
Rae, Jack W., Borgeaud, Sebastian, Cai, Trevor, Millican, Katie, Hoffmann, Jordan, Song, Francis, Aslanides, John, Henderson, Sarah, Ring, Roman, Young, Susannah, Rutherford, Eliza, Hennigan, Tom, Menick, Jacob, Cassirer, Albin, Powell, Richard, Driessche, George van den, Hendricks, Lisa Anne, Rauh, Maribeth, Huang, Po-Sen, Glaese, Amelia, Welbl, Johannes, Dathathri, Sumanth, Huang, Saffron, Uesato, Jonathan, Mellor, John, Higgins, Irina, Creswell, Antonia, McAleese, Nat, Wu, Amy, Elsen, Erich, Jayakumar, Siddhant, Buchatskaya, Elena, Budden, David, Sutherland, Esme, Simonyan, Karen, Paganini, Michela, Sifre, Laurent, Martens, Lena, Li, Xiang Lorraine, Kuncoro, Adhiguna, Nematzadeh, Aida, Gribovskaya, Elena, Donato, Domenic, Lazaridou, Angeliki, Mensch, Arthur, Lespiau, Jean-Baptiste, Tsimpoukelli, Maria, Grigorev, Nikolai, Fritz, Doug, Sottiaux, Thibault, Pajarskas, Mantas, Pohlen, Toby, Gong, Zhitao, Toyama, Daniel, d'Autume, Cyprien de Masson, Li, Yujia, Terzi, Tayfun, Mikulik, Vladimir, Babuschkin, Igor, Clark, Aidan, Casas, Diego de Las, Guy, Aurelia, Jones, Chris, Bradbury, James, Johnson, Matthew, Hechtman, Blake, Weidinger, Laura, Gabriel, Iason, Isaac, William, Lockhart, Ed, Osindero, Simon, Rimell, Laura, Dyer, Chris, Vinyals, Oriol, Ayoub, Kareem, Stanway, Jeff, Bennett, Lorrayne, Hassabis, Demis, Kavukcuoglu, Koray, Irving, Geoffrey
Natural language communication is core to intelligence, as it allows ideas to be efficiently shared between humans or artificially intelligent systems. The generality of language allows us to express many intelligence tasks as taking in natural language input and producing natural language output. Autoregressive language modelling -- predicting the future of a text sequence from its past -- provides a simple yet powerful objective that admits formulation of numerous cognitive tasks. At the same time, it opens the door to plentiful training data: the internet, books, articles, code, and other writing. However this training objective is only an approximation to any specific goal or application, since we predict everything in the sequence rather than only the aspects we care about. Yet if we treat the resulting models with appropriate caution, we believe they will be a powerful tool to capture some of the richness of human intelligence. Using language models as an ingredient towards intelligence contrasts with their original application: transferring text over a limited-bandwidth communication channel. Shannon's Mathematical Theory of Communication (Shannon, 1948) linked the statistical modelling of natural language with compression, showing that measuring the cross entropy of a language model is equivalent to measuring its compression rate.
Challenges in Detoxifying Language Models
Welbl, Johannes, Glaese, Amelia, Uesato, Jonathan, Dathathri, Sumanth, Mellor, John, Hendricks, Lisa Anne, Anderson, Kirsty, Kohli, Pushmeet, Coppin, Ben, Huang, Po-Sen
Large language models (LM) generate remarkably fluent text and can be efficiently adapted across NLP tasks. Measuring and guaranteeing the quality of generated text in terms of safety is imperative for deploying LMs in the real world; to this end, prior work often relies on automatic evaluation of LM toxicity. We critically discuss this approach, evaluate several toxicity mitigation strategies with respect to both automatic and human evaluation, and analyze consequences of toxicity mitigation in terms of model bias and LM quality. We demonstrate that while basic intervention strategies can effectively optimize previously established automatic metrics on the RealToxicityPrompts dataset, this comes at the cost of reduced LM coverage for both texts about, and dialects of, marginalized groups. Additionally, we find that human raters often disagree with high automatic toxicity scores after strong toxicity reduction interventions -- highlighting further the nuances involved in careful evaluation of LM toxicity.
Evaluating the Apperception Engine
Evans, Richard, Hernandez-Orallo, Jose, Welbl, Johannes, Kohli, Pushmeet, Sergot, Marek
The Apperception Engine is an unsupervised learning system. Given a sequence of sensory inputs, it constructs a symbolic causal theory that both explains the sensory sequence and also satisfies a set of unity conditions. The unity conditions insist that the constituents of the theory - objects, properties, and laws - must be integrated into a coherent whole. Once a theory has been constructed, it can be applied to predict future sensor readings, retrodict earlier readings, or impute missing readings. In this paper, we evaluate the Apperception Engine in a diverse variety of domains, including cellular automata, rhythms and simple nursery tunes, multi-modal binding problems, occlusion tasks, and sequence induction intelligence tests. In each domain, we test our engine's ability to predict future sensor values, retrodict earlier sensor values, and impute missing sensory data. The engine performs well in all these domains, significantly outperforming neural net baselines and state of the art inductive logic programming systems. These results are significant because neural nets typically struggle to solve the binding problem (where information from different modalities must somehow be combined together into different aspects of one unified object) and fail to solve occlusion tasks (in which objects are sometimes visible and sometimes obscured from view). We note in particular that in the sequence induction intelligence tests, our system achieved human-level performance. This is notable because our system is not a bespoke system designed specifically to solve intelligence tests, but a general-purpose system that was designed to make sense of any sensory sequence.
Undersensitivity in Neural Reading Comprehension
Welbl, Johannes, Minervini, Pasquale, Bartolo, Max, Stenetorp, Pontus, Riedel, Sebastian
Current reading comprehension models generalise well to in-distribution test sets, yet perform poorly on adversarially selected inputs. Most prior work on adversarial inputs studies oversensitivity: semantically invariant text perturbations that cause a model's prediction to change when it should not. In this work we focus on the complementary problem: excessive prediction undersensitivity, where input text is meaningfully changed but the model's prediction does not, even though it should. We formulate a noisy adversarial attack which searches among semantic variations of the question for which a model erroneously predicts the same answer, and with even higher probability. Despite comprising unanswerable questions, both SQuAD2.0 and NewsQA models are vulnerable to this attack. This indicates that although accurate, models tend to rely on spurious patterns and do not fully consider the information specified in a question. We experiment with data augmentation and adversarial training as defences, and find that both substantially decrease vulnerability to attacks on held out data, as well as held out attack spaces. Addressing undersensitivity also improves results on AddSent and AddOneSent, and models furthermore generalise better when facing train/evaluation distribution mismatch: they are less prone to overly rely on predictive cues present only in the training set, and outperform a conventional model by as much as 10.9% F1.
Making sense of sensory input
Evans, Richard, Hernandez-Orallo, Jose, Welbl, Johannes, Kohli, Pushmeet, Sergot, Marek
This paper attempts to answer a central question in unsupervised learning: what does it mean to "make sense" of a sensory sequence? In our formalization, making sense involves constructing a symbolic causal theory that explains the sensory sequence and satisfies a set of unity conditions. This model was inspired by Kant's discussion of the synthetic unity of apperception in the Critique of Pure Reason. On our account, making sense of sensory input is a type of program synthesis, but it is unsupervised program synthesis. Our second contribution is a computer implementation, the Apperception Engine, that was designed to satisfy the above requirements. Our system is able to produce interpretable human-readable causal theories from very small amounts of data, because of the strong inductive bias provided by the Kantian unity constraints. A causal theory produced by our system is able to predict future sensor readings, as well as retrodict earlier readings, and "impute" (fill in the blanks of) missing sensory readings, in any combination. We tested the engine in a diverse variety of domains, including cellular automata, rhythms and simple nursery tunes, multi-modal binding problems, occlusion tasks, and sequence induction IQ tests. In each domain, we test our engine's ability to predict future sensor values, retrodict earlier sensor values, and impute missing sensory data. The Apperception Engine performs well in all these domains, significantly out-performing neural net baselines. We note in particular that in the sequence induction IQ tasks, our system achieved human-level performance. This is notable because our system is not a bespoke system designed specifically to solve IQ tasks, but a general purpose apperception system that was designed to make sense of any sensory sequence.
Achieving Verified Robustness to Symbol Substitutions via Interval Bound Propagation
Huang, Po-Sen, Stanforth, Robert, Welbl, Johannes, Dyer, Chris, Yogatama, Dani, Gowal, Sven, Dvijotham, Krishnamurthy, Kohli, Pushmeet
Previous work has used adversarial training and data augmentation to partially mitigate such brittleness, but these are unlikely to find worst-case adversaries due to the complexity of the search space arising from discrete text perturbations. In this work, we approach the problem from the opposite direction: to formally verify a system's robustness against a predefined class of adversarial attacks. We study text classification under synonym replacements or character flip perturbations. We propose modeling these input perturbations as a simplex and then using Interval Bound Propagation - a formal model verification method. We modify the conventional log-likelihood training objective to train models that can be efficiently verified, which would otherwise come with exponential search complexity. The resulting models show only little difference in terms of nominal accuracy, but have much improved verified accuracy under perturbations and come with an efficiently computable formal guarantee on worst case adversaries. 1 Introduction Deep models have been shown to be vulnerable against adversarial input perturbations (Szegedy et al., 2013; Kurakin et al., 2016). Small, semantically invariant input alterations can lead to drastic changes in predictions, leading to poor performance on adversarially chosen samples. Recent work (Jia and Liang, 2017; Belinkov and Bisk, 2018; Ettinger et al., 2017) also exposed the vulnerabilities of neural NLP models, e.g. with small
Jack the Reader - A Machine Reading Framework
Weissenborn, Dirk, Minervini, Pasquale, Dettmers, Tim, Augenstein, Isabelle, Welbl, Johannes, Rocktäschel, Tim, Bošnjak, Matko, Mitchell, Jeff, Demeester, Thomas, Stenetorp, Pontus, Riedel, Sebastian
Many Machine Reading and Natural Language Understanding tasks require reading supporting text in order to answer questions. For example, in Question Answering, the supporting text can be newswire or Wikipedia articles; in Natural Language Inference, premises can be seen as the supporting text and hypotheses as questions. Providing a set of useful primitives operating in a single framework of related tasks would allow for expressive modelling, and easier model comparison and replication. To that end, we present Jack the Reader (Jack), a framework for Machine Reading that allows for quick model prototyping by component reuse, evaluation of new models on existing datasets as well as integrating new datasets and applying them on a growing set of implemented baseline models. Jack is currently supporting (but not limited to) three tasks: Question Answering, Natural Language Inference, and Link Prediction. It is developed with the aim of increasing research efficiency and code reuse.