Abstract This study investigates the differential effects of Textual Enhancement (TE) on the learning and unlearning of two syntactic properties of Spanish – the absence of the Pre-possessive Determiner Article (PPDA) and the presence of the Prepositional Accusative (PA) – which each pose specific acquisitional difficulties for Italian-speaking learners of Spanish (ISS) due to their asymmetrical relationships with corresponding L1 structures. 77 ISS were divided in two experimental groups: group A read 5 texts with TE on PA – the feature to be learned – and group B read the same 5 texts with TE on PPDA – the feature to be unlearned. The participants took a timed grammatical judgment task three times (before, five days after, and two months after the instructional treatment). The results are compared with those of Della Putta (2016), a symmetrical study to this, in which the same teaching intervention and experimental conditions were adopted with Spanish-speaking learners of Italian, whose task was to unlearn PA and to learn PPDA. The bidirectional comparison shows a similar, weak effect of TE, although in the present study, unlike in Della Putta (2016), unlearning did not seem to be more difficult than learning. These similarities and differences are discussed and theoretically motivated.