Menstrual cycle affects kinesthetic aftereffect, an index of personality and perceptual style

Research suggests that kinesthetic aftereffect (KAE) scores reflect status on a postulated stimulus intensity modulation (SIM) mechanism that damps down subjective stimulus intensity for some (reducing) and increases it for others (augmenting). Such a mechanism would help account for empirically observed individual differences in such behaviors as pain tolerance, sensory deprivation reactivity, and stimulation seeking. It was hypothesized and confirmed in three adult female samples that KAE varies curvilinearly over the menstrual cycle: Greater KAE reduction occurs at the cycle's beginning and end. Neither tiredness, oral contraception, medication, attention, nor social expectations can explain this finding. Of the behaviors studied in the KAE literature, only five are also encompassed by the menstrual cycle literature. Four of these (antisocial behavior, acute schizophrenic episodes, accidents, and activity level) show similar curvilinearity over the cycle. We hypothesize that cyclical variation in the SIM mechanism mediates the curvilinear pattern observed for both these four behaviors and KAE.     

A cusp catastrophe: Hysteresis, bimodality, and inaccessibility in rabbit eyelid conditioning

Three properties of the cusp catastrophe: bimodality, inaccessibility, and hysteresis were evaluated in rabbit eyelid conditioning. Bimodality was evidenced by the fact that responding tended to occur at either very low or very high levels, and inaccessibility by the fact that intermediate levels of responding were rarely encountered. Hysteresis was demonstrated when: (a) levels of responding attained under a continuous schedule of reinforcement were largely maintained by a schedule which was too lean to promote conditioning by itself; and (b) levels of responding attained with a high intensity unconditional stimulus were largely maintained by a lower intensity unconditional stimulus which was too weak to promote conditioning in its own right. These results are consistent with the model of conditioning suggested by P. W. Frey and R. J. Sears (Psychological Review, 1978, 85, 321–340) which postulates response-mapping rules based on the cusp catastrophe.