The laugh- and/or smile-evoking potency of laughter was evaluated by observing responses of 128 subjects in three undergraduate psychology classes to laugh stimuli produced by a “laugh box.” Subjects recorded whether they laughed and/or smiled during each of 10 trials, each of which consisted of an 18-sec sample of laughter, followed by 42 sec of silence. Most subjects laughed and smiled in response to the first presentation of laughter. However, the polarity of the response changed quickly. By the 10th trial, (...) few subjects laughed and/or smiled, and most found the stimulus “obnoxious.” Although other research has described canned-laughter effects, it did not consider the hypothesis confirmed here, that laughter itself evokes laughter, perhaps by activating a laughter-specific auditory-feature detector. This result is relevant to the neurological basis of social communication, human ethology, and theories of speech production and perception. (shrink)

A converging pattern of evidence from laughter, tickling, and motherese suggests that bipedal locomotion plays a critical and unanticipated role in vocal evolution. Bipedalism frees the thorax of its support role during quadrupedal locomotion, which permits the uncoupling of breathing and striding necessary for the subsequent selection for vocal virtuosity and speech.

The sclera, the eye’s tough outer layer, is, among primates, white only in humans, providing the ground necessary for the display of colors that vary in health and disease. The current study evaluates scleral color as a cue of socially significant information about health, attractiveness, and age by contrasting the perception of eyes with normal whites with copies of those eyes whose whites were reddened, yellowed, or further whitened by digital editing. Individuals with red and yellow sclera were rated to (...) be less healthy, less attractive, and older than individuals with untinted control sclera. Individuals with whitened, “super-white” sclera were rated as younger, although not more healthy or attractive, than controls. In humans, clear, white sclera may join such traits as smooth skin and long, lustrous hair as signs of health, beauty, and reproductive fitness. The evolution of a white sclera may have contributed to the emergence of humans as a social species. (shrink)

Infectious yawning and laughing offer a convenient, noninvasive approach to the evolution, development, production, and control of imitation-like and mirror-like phenomena in normal, behaving humans.

Intention, shared or unshared, is based on the presumption of unknowable and unnecessary motives and mental states in ourselves and others.

Crying and laughter are innate, preverbal, species-typical vocalizations that have similarities and differences which are mutually illuminating.

The emotional expression of laughter in opera scores and performance was evaluated by converting notation to temporal data and contrasting it with the conversational laughter it emulates. The potency of scored and sung laughter was assayed by its ability to trigger contagion in audiences.

Laughing, humor, and tickling, but not tearing and crying, involve the give-and-take that provides value and a basis for exchange in the psychosexual marketplace.