Brain in a Vat has written about a new study that examined how an author’s place in a list of authors on a peer reviewed paper affected perceptions of the relative merit.
Here’s one conclusion based on the article:
As expected, survey respondents rated first authors the highest in terms of work performed while rating last authors the highest in terms of initial conception and supervision. However, increasing the number of authors from three to five decreased the perceived contributions of the first and middle authors while having no significant effect on the perceived contribution of the last author.