Strength and physical fitness predict the perception of looming sounds

Listeners consistently perceive approaching sounds to be closer than they actually are and perceptually underestimate the time to arrival of looming sound sources. In a natural environment, this underestimation results in more time than expected to evade or engage the source and affords a “margin of safety” that may provide a selective advantage. However, a key component in the proposed evolutionary origins of the perceptual bias is the appropriate timing of anticipatory motor behaviors. Here we show that listeners with poorer physical fitness respond sooner to looming sounds and with a larger margin of safety than listeners with better physical fitness. The anticipatory perceptual bias for looming sounds is negatively correlated with physical strength and positively correlated with recovery heart rate (a measure of aerobic fitness). The results suggest that the auditory perception of looming sounds may be modulated by the response capacity of the motor system.     

Experimental and Analytical Studies of Pteridophytes: XXI. Investigations on Marsilea

An account is given of the effects of various concentrationsof glucose, sucrose, and fructose on the development and morphologyof aseptic cultures of Marsilea sporelings. The response ofthe sporelings to a range of different sugars and to growthin liquid or on solid media is also described. The results are discussed with special reference to the relationshipbetween nutrition and heteroblastic leaf development. Otheraspects of the influence of various sugars on the growth ofplants in aseptic culture are considered in relation to theexisting literature.