Online titles that use words efficiently and offer a moderate amount of information attract more clicks to read than titles that are inefficient or offer insufficient or excessive amount of information, according to the theory of just enough information, which predicts an inverted U effect of title length on read. The theory of selective spiral implies a linearly positive effect of read on relay, which predicts a mediated curvilinearity that carries the inverted U effect over to relay, making the lengthrelay effect also inverted-U. We found support for the main predictions from nearly 80 thousand postings crawled from Toutiao.com, the largest news disseminating site in Chinese.

The optimal title length for attracting read (OTRead) was over 26 Chinese characters or about 13 Chinese words, which may serve as an indicator of collective attention span. The mean and median title lengths were about 18 characters and optimal title length for relay was nearly 19 characters, representing sizable underestimations by writers and relayers of readers’ appetite for information. We propose sender insensitivity and auto superiority as possible causes of the bias.

The study also represents a couple methodological adaptations, including adopting percentage coefficients (bp) as effect size measure for big data, and employing significance tests for minimum screening rather than population inference.