Blame the Usual Contexts: New Findings on Illusory Contours and Visual Masked Priming by using Novel Contexts

Perception depends on the context, and this is why different contexts are likely to induce different perceptions. Therefore, the role of the researcher is to identify which contexts may enable her/him to draw conclusions on mechanisms underlying perception. After all, the difference between the control and the experimental condition in scientific research can be seen as a change in a specific aspect of the context: all being equal, except the independent variable. The importance of the context in perception is perhaps secondary only to its vastness and complexity. Here, we choose two distinct topics as research issues: an "old" problem, the formation of illusory contour surfaces, and a "new" one, the origins of visual masked priming. Illusory contours have been widely researched: Purghé and Coren (1992) counted more than 400 publications from 1900 to 1990. However, just a few of them deal with heterogeneous contexts, i.e., illusory contour inducers depicted against non-homogeneous backgrounds. In the first part of this work we illustrated five experiments which attempt to fill this gap. Our results confirmed previous findings found employing homogeneous contexts, and extended them to heterogeneous contexts, introducing new issues. In the second part of this work, we report a series of visual masked priming experiments that focused on between-trials factors: namely, frequency of occurrence and presentation order effects. Previous research on priming has taken into account primarily the frequency of congruent and incongruent trials, and in particular the prime validity effect: when the proportion of valid trials is higher than invalid trials, an increase in priming is obtained. However, standard randomization of trials was usually employed for presentation, making frequent trials more likely to occur on the initial trials. Thus, the effects of initial and overall trial frequencies have become intermingled. The new context employed here (a biased presentation order) shed some light on these effects. Results are in agreement with the recently proposed retroactive view of masked priming, in contrast to the classic spreading activation theories (Masson & Bodner, 2003).