B.2.7.2.1. Correlation

The WM effects on attentional orienting and on AC were correlated in the present experiments. This suggested that resisting to interference and orienting attention endogenously depended on some common processes. First, one might argue that the correlation, even if significant, was weak (r² = .26). This was true but not completely unexpected and several elements could have participated in lowering this correlation. First, the time to discriminate a target after an orienting based on an arrow cue might not be the best indicator of endogenous orienting. Indeed, some data suggested that an arrow cue might actually control orienting in an involuntary way, probably on the basis of some over-learned associations (Hommel, Pratt, Colzato, & Godijn, 2001). Second, the task simplicity, as well as the homogeneity of the participants (all young students) might have reduced the inter-individual RTs variability, which is necessary to evidence substantial correlations. Third, a threshold effect was also very probable. Indeed, each process (simple attentional orienting and resisting interference) might remain rather efficient for moderate WM loads, perhaps as long as this latter did not deactivated the related goal too much. On the contrary, they could begin to be disrupted, when exceeding a certain threshold. As argued before, this threshold would probably be different for the two conditions, given that they do not need the same amount of endogenous activation to be achieved efficiently. As WM abilities varied amongst the participants (Conway, Kane, & Engle, 2003), one might expect some low WM span participants to be perturbed in both conditions, whereas some high WM span participants might be hampered only for the more difficult salient distractor condition, while performing efficiently when the salient distractor was absent. Such a phenomenon would also strongly lower the coefficient of correlation. Thus, the rather low correlation observed could still be considered important. It suggested that WM load influenced endogenous orienting and resisting interference in a similar fashion.