We report a laboratory experiment on strategic manipulation in positional rules, by which individuals are asked to elicit a complete ranking over 3 alternatives. The prominent rule in this set is the so-called Borda Count, but our experiment also considers other rules in which we increase the score associated to the second-best candidate and vary the monetary prizes in case of a victory of the latter (“preference intensity”). Our results suggest that, as standard game-theoretic logic would suggest, when the intermediate scores and prizes increase, strategic manipulation is reduced. We also see that group size affects the likelihood of strategic manipulation in a non-linear fashion, and mostly depends on how the intermediate score is manipulated. Furthermore, rule efficiency increases with group size (i.e., as the probability of being pivotal decreases) and with both the intermediate scores and prizes.