Chimpanzees’ use of conspecific cues in matching-to-sample tasks: public information use in a fully automated testing environment

Social animals have much to gain from observing and responding appropriately to the actions of their conspecific group members. This can in turn lead to the learning of novel behavior patterns (social learning) or to foraging, ranging, or social behavioral choices copied from fellow group members, which do not necessarily result in long-term learning, but at the time represent adaptive responses to environmental cues (public information use). In the current study, we developed a novel system for the study of public information use under fully automated conditions. We modified a classic single-subject laboratory paradigm—matching-to-sample (MTS)—and examined chimpanzees’ ability to interpret and utilize cues provided by the behavior of a conspecific to solve the task. In Experiment 1, two subjects took turns on an identity MTS task, with one subject (the model) performing the first half of the trial and the other subject (the observer) completing the trial using the model’s actions as discriminative cues. Both subjects performed above chance from the first session onwards. In Experiment 2, the subjects were tested on a symbolic version of the same MTS task, with one subject showing spontaneous transfer. Our study establishes a novel method for examining public information use within a highly controlled and automated setting.     

Childhood Social Withdrawal,Interpersonal Impairment,and Young Adult Depression: A Mediational Model

Building on interpersonal theories of depression, the current study sought to explore whether early childhood social withdrawal serves as a risk factor for depressive symptoms and diagnoses in young adulthood. The researchers hypothesized that social impairment at age 15 would mediate the association between social withdrawal at age 5 and depression by age 20. This mediational model was tested in a community sample of 702 Australian youth followed from mother’s pregnancy to youth age 20. Structural equation modeling analyses found support for a model in which childhood social withdrawal predicted adolescent social impairment, which, in turn, predicted depression in young adulthood. Additionally, gender was found to moderate the relationship between adolescent social impairment and depression in early adulthood, with females exhibiting a stronger association between social functioning and depression at the symptom and diagnostic level. This study illuminates one potential pathway from early developing social difficulties to later depressive symptoms and disorders.     

ChoiceKey: A real-time speech recognition program for psychology experiments with a small response set

Psychological experiments often collect choice responses using buttonpresses. However, spoken responses are useful in many cases—for example, when working with special clinical populations, or when a paradigm demands vocalization, or when accurate response time measurements are desired. In these cases, spoken responses are typically collected using a voice key, which usually involves manual coding by experimenters in a tedious and error-prone manner. We describe ChoiceKey, an open-source speech recognition package for MATLAB. It can be optimized by training for small response sets and different speakers. We show ChoiceKey to be reliable with minimal training for most participants in experiments with two different responses. Problems presented by individual differences, and occasional atypical responses, are examined, and extensions to larger response sets are explored. The ChoiceKey source files and instructions may be downloaded as supplemental materials for this article from brm.psychonomic-journals.org/content/supplemental.     

Structural equations and causation: six counterexamples

Hall [(2007), Philosophical Studies, 132, 109–136] offers a critique of structural equations accounts of actual causation, and then offers a new theory of his own. In this paper, I respond to Hall’s critique, and present some counterexamples to his new theory. These counterexamples are then diagnosed.

Evaluating the Evidence for the General Factor of Personality across Multiple Inventories

A general factor of personality (GFP) has been proposed as the apex of a personality trait hierarchy that explains covariance among the lower-order factors measured by various personality inventories. In this study we evaluated the GFP hypothesis across several personality inventories, unlike most previous research in which the GFP has been derived from individual instruments in isolation. Exploratory analyses did not produce substantial evidence for the existence of a single cross-instrument higher-order factor of factors and efforts to specify a range of GFP-inspired models in a confirmatory framework led to significant estimation difficulties and poor fit to the data. Overall these results fail to support a common GFP that is positioned at the top of a personality trait hierarchy.     

Experience with proactive interference diminishes its effects: mechanisms of change

In three experiments, we examined the mechanisms by which prior experience with proactive interference (PI) diminished its effects. Cued recall tasks conforming to an A–B, A–D paradigm were used to induce PI effects. Experiment 1 showed that reduced PI was not due to a reduction in attention to the source of PI. Experiment 2 revealed that participants’ awareness of PI effects on memory performance increased with experience, resulting in a shift in encoding processes. Experiment 3 demonstrated that changes in encoding provided additional support for recollection that further enhanced participants’ ability to constrain their retrieval processing to the appropriate source of information at the time of test. These results can be interpreted as showing that experience with PI enhances awareness of its effects and allows individuals to adjust their learning and retrieval strategies to compensate for such effects.