The most commonly cited descriptions of the behavioral characteristics of habituation come from two papers published almost 40 years ago (Thompson and Spencer, 1966;Groves and Thompson, 1970). In August 2007, the authors of this review, who study habituation in a wide range of species and paradigms, met to discuss their work on habituation and to revisit and refine the characteristics of habituation. This review offers a re-evaluation of the characteristics of habituation in light of these discussions. We made substantial changes to only a few of the characteristics, usually to add new information and expand upon the description rather than to substantially alter the original point.In the 20 th century, great progress was made in understanding the behavioral characteristics of habituation. A landmark paper published by Thompson and Spencer in 1966 clarified the definition of habituation, synthesized the research to date and presented a list of nine behavioral characteristics of habituation that appeared to be common in all organisms studied The history of habituation and the historical context of Thompson & Spencer's (1966) distillation are reviewed more fully in an article by Thompson (2009) that is included in this issue. This list was repeated and expanded upon by Groves and Thompson in 1970. These two papers are now citation classics and are considered to be the authorities on the characteristics of habituation. In August 2007, a group of 15 researchers (the authors of this review) who study habituation in a wide range of species and paradigms met to revisit these characteristics and refine them based on the 40 years of research since Thompson and Spencer 1966. The descriptions and characteristics from 1966 have held up remarkably well, and the revisions we have made to them were often for clarity rather than content. We made substantial changes to only a few of the characteristics, usually to add new information and expand upon the description rather than to substantially alter the original point. We restricted ourselves to an analysis of habituation; there was insufficient time for detailed discussions of the other form of non-associative learning "sensitization." Thus this review is restricted to our discussions of habituation and dishabituation (as it relates directly to habituation).Many people will be surprised to learn that, although habituation is termed "the simplest form of learning" and is well studied behaviorally, remarkably little is known about the neural mechanisms underlying habituation. Researchers who work on this form of learning believe that because habituation allows animals to filter out irrelevant stimuli and focus selectively on

Over the past decade, the study of attention in infancy has seen dramatic progress. This review delineates four attentional functions (alertness, spatial orienting, attention to object features, and endogenous attention) that are relevant to infancy and uses these functions as a framework for summarizing the developmental course of attention in infancy. Rudimentary forms of various attentional functions are present at birth, but each of the functions exhibits different and apparently dissociable periods of postnatal change during the first years of life. The role of attention in development should therefore be considered in the context of interaction among different systems at different levels of maturity during the first years of life.

A supplement of 600 mg DHA/d in the last half of gestation resulted in overall greater gestation duration and infant size. A reduction in early preterm and very-low birth weight could be important clinical and public health outcomes of DHA supplementation. This trial was registered at clinicaltrials.gov as NCT00266825.

The use of visual habituation in the study of infant cognition and learning is reviewed. This article traces the history of the technique, underlying theory, and procedural variation in its measurement. In addition, we review empirical findings with respect to the cognitive processes that presumably contribute to habituation, studies of developmental course and long-term prediction, as well as recent attempts to address or explain the phenomenon of visual habituation through the use of mathematical or quantitative models. The review ends with an appeal for a return to the study of habituation per se as a valid measure of infant learning, rather than relegating the phenomenon to its use as a technique for familiarizing infants in procedures testing for discrimination or recognition.