“…Furthermore, for the mirror-image design to provide support for the TPM, it has to show that the two groups behave the same (that is, transfer from the same language, whether it is the L1 or the L2 of the participants). And, while null results are not impossible to interpret statistically, it is not straightforward to argue that lack of significant differences between the groups means that order of acquisition does not play a role (for a similar argument, see Lago et al, 2021). Finally, depending on the language combinations, mirror-image groups are very difficult -and in many cases impossible -to find.…”