Maximum Positive Score Research Articles

Some studies of comparative aspects of sexual behaviour in ponies and donkeys

The external manifestations of oestrus are said to be characteristic of the species. A comparative study of the cyclic sexual behaviour of eight pony mares ( Equus caballus) and five donkey mares ( Equus asinus) demonstrated significant differences in the signs of oestrus in the two species. A scoring system was designed to quantify the intensity of oestrus. In the pony, a maximum positive score was obtained when the mare showed an obvious interest in the stallion, adopted an acceptance stance with the tail held away from the perineum, and repeatedly retracted the vulval lips to evert the clitoris, often squirting out small amounts of urine or mucus. Aggressive or threatening behaviour, with the tail swishing or clamped against the perineum, received a negative score. This scoring system was then adapted to the sexual behaviour of the donkey. The most significant difference was that during oestrus the donkey mares exhibited a characteristic facial expression, involving a repeated raising and lowering of the mandible with the neck extended and ears depressed, when stimulated by the sight or sound of the stallion.

Payoff: A Neglected Factor in Reaction Time Measurement

The aim of this paper is to point out some implications of implicit or explicit payoffs in reaction time experiments. In any psychophysical task the subject is given a set of instructions which define the desired performance, as it were the rules of the game. Instructions may be supplemented by knowledge of results which further define the required performance. When performance admits of being “good” or “bad,” however wide these limits, the instructions may be said to define, explicitly or implicitly, a system of payoffs. In reaction time experiments the subject is instructed, amongst other things, to respond as soon as possible after the stimulus but never before it. These instructions could equally well be represented by a system of payoffs and Figure 1 illustrates the kind of payoff system normally implied in these instructions. If S represents the time at which the physical stimulus occurs the graph shows a fixed penalty for anticipations (response before S), maximum positive score for responses immediately following S declining at an arbitrary rate as a function of elapsed time between S and the response until an unacceptably long time involves a constant maximum penalty. Some experimenters choose to treat very short RT's as anticipations. This is represented by the dashed line in Figure 1, but it should be clear that payoff values are, to a certain extent, arbitrary.