State anxiety: construct and measuresThe compelling observation that specific unpleasant emotional conditions, characterized by short-lived feelings of tension or apprehension, are actually prone to fluctuations depending on external contingencies in the environment was first put forward by Cattell (1966;Cattell & Scheirer, 1958& 1963 in the second half of the last century, when he proposed the distinction between state anxiety and a more stable personality trait (referred to as trait anxiety), the latter being related to the tendency to experience feelings of tension and worrisome thoughts. Since this pioneering work, although no consensus has been reached about the true nature of state anxiety as a psychological or physiological construct, this concept has been further elaborated and refined by Spielberger (1966Spielberger ( & 1976 at a theoretical level, and it has been implicated in a myriad of empirical studies that have helped delineate and better characterize the numerous psychological reactions to stressors in humans (e.g., , or the physiological activations of the nervous system triggered by external or internal emotional stimuli (e.g., Swartzman, Edelberg, & Kemman, 1990;de Rooij, Schene, Phillips, & Roseboom, 2010). Levels of trait anxiety are considered crucial for people's successful adaptation to the environment, and have been shown to influence a multitude of core psychological components, including well-being and mental health (e.g., Duncko, Makatsori, Fickova, Selco, & Jezova, 2006;Bruk-Lee, Khoury, Nixon, Goh, & Spector, 2009). Consequently, good instruments for measuring stable inter-individual differences in anxiety proneness, considered as a personality trait, have been developed in the affective sciences literature (e.g., Cattel & Scheirer, 1963;Spielberger, Gorsuch, & Lushene, 1970), with the underlying idea that such trait is long lasting and mostly stable across time and situations. At the same time, a 4 growing number of studies suggested that trait characteristics of anxiety not always accurately predicted psychological responses in specific situations (e.g., , nor did they always show a straightforward relationship with the magnitude of anxiety fluctuations over time in response to external events (see Spielberger, 1983;. In these cases, a less stable measure of anxiety, able to capture these short-lived variations in the state of the individual would be desirable.In order to appropriately meet these theoretical and empirical considerations, several instruments have been developed over the years, providing alternative instruments for measuring state-dependent fluctuations in anxiety, or more broadly, in affect or mood. for the POMS). Moreover, systematically comparing the psychometric properties of each measure seems rather difficult, since they have to be retrieved from various and sometimes scattered sources, such as the manuals and a set of psychometric papers addressing different combinations of instruments, with sometimes a lack of consistency across analysis techniques, sample...