Additivity Pretraining and cue competition effects: Developmental evidence for a reasoning account of causal learning

The effect of additivity pretraining on blocking has been taken as evidence for a reasoning account of human and animal causal learning. If inferential reasoning underpins this effect, then developmental differences in the magnitude of this effect in children would be expected. Experiment 1 examined cue competition effects in children's (4- to 5-year-olds and 6- to 7-year-olds) causal learning using a new paradigm analogous to the food allergy task used in studies of human adult causal learning. Blocking was stronger in the older than the younger children, and additivity pretraining only affected blocking in the older group. Unovershadowing was not affected by age or by pretraining. In experiment 2, levels of blocking were found to be correlated with the ability to answer questions that required children to reason about additivity. Our results support an inferential reasoning explanation of cue competition effects. (c) 2012 APA, all rights reserved.

Importance of consumers on exposed and sheltered rocky shores.

It is often suggested that the relative importance of biotic processes, such as recruitment, competition and predation of marine benthic species, varies predictably along a gradient of exposure to wave action. Several established models of community dynamics on rocky shores predict that top-down processes are more important for structuring communities on sheltered than on exposed shores. To test the relative dominance of top-down processes, we first measured the establishment of key benthic species (mussels, barnacles and algae) on 3 sheltered and 3 exposed rocky shores in southwest Ireland over two 6 mo periods. We then manipulated the presence of consumers (e.g. grazing gastropods, crabs, whelks), using caged exclosures, on 2 sheltered and 2 exposed shores to test for an interaction between effects of consumers and shore exposure on the establishment of benthic species. In contrast to predictions, we found that consumers strongly affected establishment of all species regardless of shore exposure. We also found that shore exposure was not a reliable predictor for spatial and temporal variation in rates of establishment of sessile benthic species. Our findings provide experimental evidence which demonstrates the importance of consumers in early post-settlement stages of benthic species-essential for the development of benthic-pelagic models. © 2011 Inter-Research.


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