Autotransformation is when a toy undergoes a partial or full transformation without external manipulation beyond initial activation. Certain classes of Transformer toys are defined largely by their autotransformation mechanisms. These include the following:
Other toys may include autotransformation as a secondary feature. For example, Armada Optimus Prime's trailer is designed to autotransform when it receives an infrared signal from the manually-transformable cab. Partial autotransformation was a large part of the 2007 movie line, where it was referred to as "Automorph Technology".
Transformers fiction has sometimes presented characters whose toys autotransform as having the ability to transform unusually quickly. For example, the Battlechargers were said to transform "more quickly than the human eye could follow".
Autotransformation is frequently reviled in online discussions, perhaps because it takes away from the mechanical-puzzle aspect of the toy, or perhaps because its mechanism tends to limit the design and articulation of the figure. Or maybe it's because it is a disgusting gimmick and gimmicks are for babies.
History of the term
The earliest use of the term "auto-transform" to be found is in the Google groups archives from July of 1996 . Other message boards of the day have, unfortunately, turned into bit-smoke and blown away in the cold, cold winds, making thorough research difficult. Judging by the nonstandardized form of the term in 1996, it was probably fairly new, and was quickly adopted, but lost its hyphen.