CHAPTER III.

OCCASIONS AND CAUSES OF LAUGHTER.

1. Laughter as provoked by sense-stimulus: tickling • 50

Ticklish areas • 52

Characteristics of the sensations of tickling • 53

Motor reactions provoked by tickling • 56

How far attributes of sensation determine laughter of tickling • 57

The mental factor in effect of tickling • 59

Objective conditions of successful tickling • 60

Tickling as appealing to a particular mood • 62

2. Other quasi-reflex forms of laughter • 64

Varieties of automatic or “nervous” laughter • 65

Common element in these varieties: relief from strain • 67

3. Varieties of joyous laughter • 70

Prolonged laughing fit • 73

The essential element in joyous laughter • 75

Occasions of joyous laughter • 76

(_a_) Play • 76

(_b_) Teasing as provocative situation • 77

(_c_) Practical joking and laughter • 78

(_d_) Laughter as an accompaniment of contest • 78

(_e_) Occasions of unusual solemnity as provoking laughter • 79

Physiological basis of laughing habit • 80