In this case, too, it is probable that we have to do, not merely with differences of precocity in the children observed, but with the difficulties of determining what is a clear example of the expression concerned.[102] There is no doubt that the full reiteration of our laughter is reached by stages. This is brought out fully by Darwin, and is allowed by Preyer. Yet how much of the series of more or less laughter-like sounds produced by an infant during states of pleasure is to be regarded as entering into the development of laughter, it is not easy to say. Miss Shinn heard Ruth give out curious little chuckling sounds of two syllables on the 105th day, that is thirteen days before she produced her {168} laugh. She adds under the date, 113th day, that is to say, five days before the laugh, that the child had developed new throat sounds, crowing, croaking, etc., and showed a strong disposition to vary sounds in a pleasurable mood. It seems highly improbable that these sounds were not preparatory stages in the development of the laugh.[103] It is fairly certain that laughing comes after smiling. Preyer’s words may no doubt seem to suggest that the first laugh (twenty-third day) comes before the first smile (twenty-sixth day); but his account of the development of the two shows plainly that this is not his meaning. He distinctly says that laughter is only a strengthened and audible (laut) smile; and remarks, further, that “in all (children) alike the utterance of pleasure begins with a scarcely noticeable smile, which quite gradually passes into laughter in the course of the first three months”. He adds that this development depends on that of the higher brain centres, and the capability of having perceptions.[104] The first laughter is, like the smile, an expression of pleasure. As Preyer puts it, the laughter is a mere heightening of the look of pleasure. It marks, however, a higher level of agreeable consciousness. Whereas the first clumsy experiments in smiling denote nothing but a comfortable state of repletion, the first attempts at laughter are responses to gladdening sense-presentations, such as swinging coloured objects, and the new sounds of a piano. This laughter at new visual and aural presentations was followed, according to Preyer, between the sixth and the {169} ninth week by a laughter more distinctly joyous or jubilant, as the child regarded his mother’s face and appeared to recognise it. This laughter of mental gaiety seems at an early age—about the fourth month—to ally itself with movements of the limbs (raising and lowering of the arms, etc.) as a complex sign of high spirits or gladness.[105]