Why successful performance in imagery tasks does not require the manipulation of mental imagery

Nanay (2017) argues for unconscious mental imagery, inter alia based on the assumption that successful performance in imagery tasks requires the manipulation of mental imagery.I challenge this assumption with the help of results presented in Shepard and Metzler (1971), Zeman et al. (2010), and Keogh and Pearson (2018).The studies suggest that imagery tasks can be successfully performed by means of cognitive/propositional strategies which do not rely on imagery.