An infant's emotional reactivity and intensity is referred to as its

Attitude refers to a person's settled way of thinking or feeling about something, typically shaped by experiences and beliefs rather than innate emotional responses. While attitudes can influence behavior, they do not directly describe the inherent emotional reactivity seen in infants.

Emotionality is a broader term that encompasses the capacity to experience and express emotions. Although related to temperament, it does not specifically capture the distinctive and consistent emotional responses that define an infant's temperament.

Heritability is a statistical concept that estimates the degree to which genetic factors contribute to individual differences in traits within a population. While temperament may have a heritable component, heritability itself does not describe the emotional reactivity of an infant but rather the genetic influences on various traits.

Personality encompasses the broader patterns of thoughts, feelings, and behaviors that make a person unique, typically developing over time through interactions with the environment. Infants exhibit temperament, which is a precursor to personality, but personality itself is not fully formed until later in life.