Updating the Baldwin effect : The biological levels behind Piaget's new theory

In 1964, Conrad Waddington (1905–1975) presented a paper in Geneva that led to an internal reassessment of the biological underpinnings of Jean Piaget's (1896–1980) theory. This in turn resulted in an overhaul of the theoretical framework upon which his stage theory of child development had been based, including his appeals to James Mark Baldwin's (1861–1934) “circular reaction.” In addition to leading to the emergence of what has elsewhere been called “Piaget's new theory,” this renovation also resulted in the update of the famous “Baldwin Effect.” Because aspects of the subsequent framework are of contemporary significance, this essay will review some of the work leading up to those updates. In reaching behind the translations to trace the sources of the arguments to which Piaget appealed, the resulting examination fills some of the gaps found in the secondary literature without quibbling over the “correct” English interpretation of translated French terms. We also go beyond how Piaget's writings have been understood in English and extract some useful additional ideas from his sources, including how to conceive of the social context in which development takes place. We see as a result how Waddington and his colleagues, including Paul Weiss (1898–1989), provided a constructive “existence proof” for the formal hierarchy of levels that Piaget had come to by other means.     

The generality of word-association hierarchies: I. Production and recall of association responses

Ss responded to a stimuluslist in a free word association session (AS) and tried to recall their response to each stimulus in a recall session (RS). There was a significant positive correlation between commonality score (Co) in AS and number of correct reproductions in RS. All Ss tended to gain in Co, but LC (i.e., Ss of low Co in AS) more than HC (i.e., Ss of high Co in AS).     

Influence of delayed muscle reflexes on spinal stability: Model-based predictions allow alternative interpretations of experimental data

Model-based calculations indicate that reflex delay and reflex gain are both important for spinal stability. Experimental results demonstrate that chronic low back pain is associated with delayed muscle reflex responses of trunk muscles. The aim of the present study was to analyze the influence of such time-delayed reflexes on the stability using a simple biomechanical model. Additionally, we compared the model-based predictions with experimental data from chronic low back pain patients and healthy controls using surface-electromyography. Linear stability methods were applied to the musculoskeletal model, which was extended with a time-delayed reflex model. Lateral external perturbations were simulated around equilibrium to investigate the effects of reflex delay and gain on the stability of the human lumbar spine. The model simulations predicted that increased reflex delays require a reduction of the reflex gain to avoid spinal instability. The experimental data support this dependence for the investigated abdominal muscles in chronic low back pain patients and healthy control subjects. Reflex time-delay and gain dependence showed that a delayed reflex latency could have relevant influence on spinal stability, if subjects do not adapt their reflex amplitudes. Based on the model and the experimental results, the relationship between muscle reflex response latency and the maximum of the reflex amplitude should be considered for evaluation of (patho) physiological data. We recommend that training procedures should focus on speeding up the delayed reflex response as well as on increasing the amplitude of these reflexes.