Abstract: We introduce a large dataset of narrative texts and questions about these texts, intended to be used in a machine comprehension task that requires reasoning using commonsense knowledge. Our dataset complements similar datasets in that we focus on stories about everyday activities, such as going to the movies or working in the garden, and that the questions require commonsense knowledge, or more specifically, script knowledge, to be answered. We show that our mode of data collection via crowdsourcing results in a substantial amount of such inference questions. The dataset forms the basis of a shared task on commonsense and script knowledge organized at SemEval 2018 and provides challenging test cases for the broader natural language understanding community.

Introduction: Ambiguity and implicitness are inherent properties of natural language that cause challenges for computational models of language understanding. In everyday communication, people assume a shared common ground which forms a basis for efficiently resolving ambiguities and for inferring implicit information. Thus, recoverable information is often left unmentioned or underspecified. Such information may include encyclopedic and commonsense knowledge. This work focuses on commonsense knowledge about everyday activities, so-called scripts. This paper introduces a dataset to evaluate natural language understanding approaches with a focus on interpretation processes requiring inference based on commonsense knowledge. In particular, we present MCScript, a dataset for assessing the contribution of script knowledge to machine comprehension. Scripts are sequences of events describing stereotypical human activities (also called scenarios), for example baking a cake or taking a bus BIBREF0 . To illustrate the importance of script knowledge, consider Example ( SECREF1 ): Without using commonsense knowledge, it may be difficult to tell who ate the food: Rachel or the waitress. In contrast, if we utilize commonsense knowledge, in particular, script knowledge about the eating in a restaurant scenario, we can make the following inferences: Rachel is most likely a customer, since she received an order. It is usually the customer, and not the waitress, who eats the ordered food. So She most likely refers to Rachel. Various approaches for script knowledge extraction and processing have been proposed in recent years. However, systems have been evaluated for specific aspects of script knowledge only, such as event ordering BIBREF1 , BIBREF2 , event paraphrasing BIBREF3 , BIBREF4 or event prediction (namely, the narrative cloze task BIBREF5 , BIBREF6 , BIBREF7 , BIBREF8 , BIBREF9 ). These evaluation methods lack a clear connection to real-world tasks. Our MCScript dataset provides an extrinsic evaluation framework, based on text comprehension involving commonsense knowledge. This framework makes it possible to assess system performance in a multiple-choice question answering setting, without imposing any specific structural or methodical requirements. MCScript is a collection of (1) narrative texts, (2) questions of various types referring to these texts, and (3) pairs of answer candidates for each question. It comprises approx. 2,100 texts and a total of approx. 14,000 questions. Answering a substantial subset of questions requires knowledge beyond the facts mentioned in the text, i.e. it requires inference using commonsense knowledge about everyday activities. An example is given in Figure FIGREF2 . For both questions, the correct choice for an answer requires commonsense knowledge about the activity of planting a tree, which goes beyond what is mentioned in the text. Texts, questions, and answers were obtained through crowdsourcing. In order to ensure high quality, we manually validated and filtered the dataset. Due to our design of the data acquisition process, we ended up with a substantial subset of questions that require commonsense inference (27.4%).

Question: how was the data collected?
Answer: The data was collected using 3 components: describe a series of pilot studies that were conducted to collect commonsense inference questions, then discuss the resulting data collection of questions, texts and answers via crowdsourcing on Amazon Mechanical Turk and gives information about some necessary postprocessing steps and the dataset validation.