The shifting sands in the effects of source text summarizability on summary writing

This paper reports the effects of the properties of source texts on summarization. One hundred and fifty-seven undergraduates were asked to write summaries of one of three extended English texts of similar length and readability, but differing in other discoursal features such as lexical diversity and macro-organization. The effects of summarizability were examined from two perspectives: students’ summarization task performance and their perception of such effects as demonstrated in the post-summarization questionnaire and interviews. Source text had significant and relatively larger effects than the summarizers’ language abilities on summarization performance. These were more pronounced on Chinese than English summarization. Perceptual data were generally supportive of the performance data and further illuminated the dynamics of the summarizability of a source text and its potential effects on performance. Macro-organization, frequency of unfamiliar words, topic familiarity, length of source texts were among the most influential factors shaping text summarizability in the view of the participants. However, the effects of summarizability proved to be rather idiosyncratic. Implications of these findings are discussed in relation to source text selection when designing summarization tasks.