Differences in preschool children's conceptual strategies when thinking about animate entities and artifacts.

Two-, 3-, and 4-year-old children viewed 10 stimulus sets. Each set contained a sample picture (e.g., a dog), a basic-level taxonomic match (e.g., another dog), a thematic match (e.g., a bone), and an irrelevant match (e.g., a pen). The children were asked to choose a match that "goes with" each sample. Sample pictures were either animate entities or artifacts. The children's choice behavior indicated that a shift occurs between 3 and 4 years of age from a taxonomic bias to a thematic bias and that, at both ages, animate sample stimuli enhance the children's tendency to adopt thematic conceptual strategies. These data are consistent with recent suggestions that thematic thinking presupposes basic-level taxonomic thinking during early conceptual development and that this developmental progression occurs more rapidly in some domains of knowledge than in others.

Computer-mediated social support: single young mothers as a model system.

Forty-two single mothers with young infants were given access to a computer-mediated social support (CMSS) network concerned with parenting issues. The network operated 24 hours per day over a period of 6 months. It permitted public message exchanges, private e-mail, and text-based teleconferencing for as many as 8 participants at any one time. During the 6 month intervention, the 42 women accessed the network over 16,670 times. Individual differences in participation were significantly associated with indices of social isolation from peers. A descriptive analyses of the messages exchanged on the network disclosed that 98% of the replies to concerns posted in the public forum provided positive social support. The majority of the supportive replies fell into the category of emotional support, followed in order by informational and tangible support. Both the self-report data following the intervention, and qualitative data extracted from online discussions indicated that close personal relationships and a sense of community developed in this novel social environment. Finally, an analysis of pretest-posttest changes in the level of parenting stress revealed that mothers who participated regularly in this CMSS community were more likely to report a decrease in parenting stress following the intervention.

Directive interactions and early vocabulary development: the role of joint attentional focus.

Maternal directiveness, assessed by the mother's use of prescriptives, is correlated with slow vocabulary development. As prescriptives are most often used to redirect a child's attention to a different object or activity, it is hypothesized that attentional regulation underlies this negative relationship. In the present study, twelve mothers were videotaped interacting with their children aged 1;1, and 100 maternal utterances were coded for pragmatic intent. Prescriptives were coded as either changing (leading) or following the child's focus of attention. Only the frequency of mothers' follow-prescriptives correlated significantly with a productive vocabulary measure taken at 1;10. This correlation was high and positive, indicating that, given joint focus, directing a 13-month-old's behaviour can have beneficial effects on subsequent vocabulary development.

Changes in a multiple-response repertoire during response-contingent punishment and response restriction: Sequential relationships.

A multiple-response baseline of four activities was established using gerbils as subjects. When one of the baseline responses was punished (Experiment 1) or restricted (Experiments 2 and 3), only the most probable of the alternative baseline responses increased. The response most likely to follow the punished or restricted responses during baseline sessions was also suppressed during subsequent punishment or response-restriction treatment.

Some effects of punishment upon unpunished responding.

Animals permitted free access to a running wheel and drinking tube increased the amount of running when drinking was punished with electric shock. Additional experiments demonstrated that the simple presence or absence of a drinking tube (or running wheel) was a sufficient condition to observe a decrease or an increase in the alternative response. A quantitative analysis of these interactions observed between the incompatible running and drinking responses suggested that each response occupied a constant proportion of the time available for it. These results question an interpretation of the increase in unpunished alternative responding based upon its avoidance properties.

Enhancement of off-key pecking by on-key punishment.

Under a variable-interval food reinforcement schedule, some of a pigeon's pecking responses land on the wall area adjacent to the response key. These off-key pecks increase in frequency when key responses produce shocks and decrease when shock is removed.