17 research outputs found
Sources of avoidance motivation: Valence effects from physical effort and mental rotation
When reaching goals, organisms must simultaneously meet the overarching goal of conserving energy. According to the law of least effort, organisms will select the means associated with the least effort. The mechanisms underlying this bias remain unknown. One hypothesis is that organisms come to avoid situations associated with unnecessary effort by generating a negative valence toward the stimuli associated with such situations. Accordingly, merely using a dysfunctional, ‘slow’ computer mouse causes participants to dislike ambient neutral images (Study 1). In Study 2, nonsense shapes were liked less when associated with effortful processing (135° of mental rotation) versus easier processing (45° of rotation). Complementing ‘fluency’ effects found in perceptuo-semantic research, valence emerged from action-related processing in a principled fashion. The findings imply that negative valence associations may underlie avoidance motivations, and have practical implications for educational/workplace contexts in which effort and positive affect are conducive to success
How ice grows from premelting films and water droplets
Close to the triple point, the surface of ice is covered by a thin liquid
layer (so-called quasi-liquid layer) which crucially impacts growth and melting
rates. Experimental probes cannot observe the growth processes below this
layer, and classical models of growth by vapor deposition do not account for
the formation of premelting films. Here, we develop a mesoscopic model of
liquid-film mediated ice growth, and identify the various resulting growth
regimes. At low saturation, freezing proceeds by terrace spreading, but the
motion of the buried solid is conveyed through the liquid to the outer
liquid-vapor interface. At higher saturations water droplets condense, a large
crater forms below, and freezing proceeds undetectably beneath the droplet. Our
approach is a general framework that naturally models freezing close to three
phase coexistence and provides a first principle theory of ice growth and
melting which may prove useful in the geosciences.Comment: 32 pages, 10 figure