Implicit and explicit processes in a hypothesis testing task

We present the results of two experiments investigating the factors that determine responding on the pseudo-diagnosticity task. In Expt I we manipulated people's beliefs about the degree to which an initial piece of evidence supported a focal hypothesis and found decreased pseudo-diagnostic (PD) responding when the evidence offered low support for the focal hypothesis. In Expt 2 we manipulated the instructions given to participants. We found that instructions to select evidence to help decide between the focal and the complementary hypotheses produced fewer PD responses than both instructions to decide whether the focal hypothesis was the case and instructions to decide whether its complement was the case. The results are interpreted within the framework of recent dual process theories of reasoning.

Children's serial recall errors: Implications for theories of short-term memory development

Three experiments examined developmental changes in serial recall of lists of 6 letters, with errors classified as movements, omissions, intrusions, or repetitions. In Experiments 1 and 2, developmental differences between groups of children aged from 7 to 11 years and adults were found in the pattern of serial recall errors. The errors of older participants were more likely to be movements than were those of younger participants, who made more intrusions and omissions. The number of repetition errors did not change with age, and this finding is interpreted in terms of a developmentally invariant postoutput response inhibition process. This interpretation was supported by the findings of Experiment 3, which measured levels of response inhibition in 7-, 9-, and 11-year-olds by comparing recall of lists with and without repeated items. Response inhibition remained developmentally invariant, although older children showed greater response facilitation (improved correct recall of adjacent repeated items). Group differences in the patterns of other errors are accounted for in terms of developmental changes in levels of output forgetting and changes in the efficiency of temporal encoding processes, (C) 2000 Academic Press.

Gender differences, responsiveness and memory of a potentially painful event in hermit crabs

Nonreflexive responses to a noxious event and prolonged memory are key criteria of a pain experience. In a previous study, hermit crabs, Pagurus bernhardus, that received a small electric shock within their shell often temporarily evacuated the shell and some groomed their abdomen and/or moved away from their vital resource. Most, however, returned to the shell. When offered a new shell 20 s later, shocked crabs were more likely than nonshocked crabs to approach and move into a new shell and did so more quickly (Elwood & Appel 2009, Animal Behaviour, 77, 1243-1246). Here we examined how increasing the time between the shock and the offering of a new shell influences the response. There was evidence of a memory of the aversive shock that lasted at least 1 day. Crabs tested after 30 min and 1 day were more likely to approach the shell and new shells were more likely to be taken 30 min after the shock. Shocked crabs approached the new shell more quickly and used fewer probes of the chelipeds prior to moving in and these results were stable over time and significant for specific times up to 1 day. Females were more likely than males to evacuate shells and did so after fewer shocks. These results extend previous work and demonstrate an extended memory of having been shocked. The findings are consistent with respect to criteria for pain that are accepted for vertebrates.