Do individual differences in sociosexuality represent genetic or environmentally contingent strategies? Evidence from the Australian twin registry

Although men are substantially more interested than women in casual sex, there is ample variation in this trait (sociosexuality) within both sexes. One theory hypothesizes that within-sex sociosexual variation results from genetic variation maintained by frequency-dependent selection. If so, sociosexuality should be substantially heritable. A competing theory is that children acquire their mating strategy after observing their parents' relationship. By this theory, sociosexuality should reveal a strong shared environmental component. The authors studied genetic and environmental influences on sociosexuality using a large, representative volunteer twin sample. Parental marital instability was modestly associated with sociosexuality, but this could have been due to either genetic or environmental factors. Consistent with genetic theory, familial resemblance appeared primarily due to additive genetic rather than shared environmental factors.     

Effect of presentation order on the construction of linear orders

Subjects constructed four-term linear orders from three sentences expressing the relationships between adjacent elements in the order. Successful performance was more likely when the second sentence introduced only one element not mentioned in the first sentence rather than two new elements and when the second and third sentences introduced new elements as grammatical subjects rather than objects. Except for the latter result, previously proposed theories of reasoning processes primarily in three-term series problems, predict other differences that failed to appear. Apparently, in longer series, memory limitations favor conditions in which each sentence after the first presents a relationship between a new and an old element in linguistic forms that identify the new element.     

MODELR—Model building and model modification for instruction

An integrated set of three computer programs that enable the implementation and student investigation of computer models of behavioral phenomena is described. These models are intended as tools for aiding in the instruction of undergraduate social science courses in research methods. Each program provides for natural language interaction with one of three classes of users: A “Modeler,” who implements a model of some behavioral phenomenon; an “Instructor,” who tailors his own or others’ models for his course of instruction; and a “Student Experimenter,” who applies an experimental design to the model and receives synthetic data in return. None of these users need have any prior computer expertise nor do they depend on external documentation on how to use the programs.     

The change from visible to invisible:

It is argued that the problem of the phenomenal persistence of objects in experience, often called “object permanence,” is actually a problem of the discriminating of persisting from nonpersisting things. A distinction is made between objects that go out of sight and objects that go out of existence, and it is shown that optical information exists to distinguish these two cases. Evidence is provided from a series of motion picture displays to suggest that Os do in fact distinguish them. The various optical transitions are shown to be reversing in the first case, but nonreversing in the second. In particular, the transition that specifies the occlusion of one surface by another is analyzed, together with the inverse of this transition. This study is a sequel to an earlier one of optical transformations.     

Habit reversal in the turtle

Two groups of mature “painted” turtles were trained in a T-maze. One group had five trials per day, with correct and incorrect turns reversed for each animal whenever it reached the criterion of five errorless trials on a given day. The second group had 10 trials per day, with correct and incorrect turns reversed daily, irrespective of the performance of the animals. Only in the data for the second group did there appear some indication of progressive improvement in habit reversal. The results are considered in relation to those obtained in analogous experiments with other species.     

Processing of text containing artificial inclusion relations

The present studies were based on the hypothesis that the majority of college students have available to them the appropriate schema for understanding set inclusion relations, but that various factors influence the likelihood that the schema is used in the processing of text containing artificial inclusion relations. Although group data did not support this hypothesis, the data of individual subjects could be readily interpreted as resulting from the selection of one of a small set of representational schemata. Among the factors shown to influence schema selection were the choice of sentence frame used to present each relation, the presence or absence of real-world contextual information, and the structure (simple vs. complex) of the underlying inclusion relation. In addition, one experiment showed that the processes used in constructing a mental representation of an inclusion relation and in retrieving information from the representation are similar to those used with linear orderings.