It is widely known that fear extinction is more vulnerable than the original fear memory, as relapse phenomena have systematically shown in the literature with different species and procedures. One strategy potentially useful to mitigate relapse is the occasional reinforced extinction treatment. In contrast to a standard procedure, this strategy consists of the inclusion of a gradual and sparse number of CS-US pairings within the standard extinction treatment, which may potentiate the effects of the latter. Although it might be a potentially useful technique, the current evidence assessing its effectiveness does not appear to be consistent. Here, we provide a comprehensive review of the available literature, highlighting differences in the relapse phenomena being studied, variables of interest and specific effects obtained. The observed methodological variability makes it difficult to draw a robust conclusion of the effectiveness of an occasional reinforced intervention to reduce different forms of relapse as the strategy has not consistently proved a general advantage over standard extinction.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
