Answer: 4 - 12 months: slower
Explanation: In the infant, two basic feelings or states of emotions begin to develop, namely, negative emotions or states of distress, and positive emotions or states of pleasure. Later in the course of development, there is a gradual differentiation of these basic states and the generation of separate emotions within these states. For example, a negative state can be expressed as sadness, food rejection, disgust, anger, etc., it is the same, i.e similar to a positive state.
The aforementioned fear occurs between the ages of 4 and 12 months, and lasts approximately 7 to 8 months. This was determined by examining children of that age, their reactions, how sensitive their mothers were, etc. It was found that fear occurs in the aforementioned period between 4 and 12 months, which is then the most visible increase in the expression of fear on the faces of infants. This led to moderation of infant temperament as well as maternal sensitivity level. The temperament of the infant changed, and with the rise of temperamental fear the reaction to fear grew. Also, with the increase of mothers' sensitivity, the feeling of fear, i.e the rate of fear over time, increased more slowly.