What term describes actions occurring as a result of a sudden inner impulse without premeditation?

The term that best describes actions occurring as a result of a sudden inner impulse without premeditation is "impulsive." Impulsive actions are characterized by spontaneity and a lack of forethought. People acting impulsively often do so in response to immediate feelings, desires, or situations without considering the consequences.

While "spontaneous" might seem similar, it doesn't fully capture the lack of thought or consideration involved in "impulsive" actions. Spontaneous actions can be planned, such as deciding to take a last-minute trip. "Reflexive" refers to automatic responses to stimuli, which also differ from the conscious decision-making aspect of impulsiveness. Finally, "deliberate" clearly stands for actions taken after careful consideration, which is the opposite of what is being described in the question.

Understanding these nuances helps clarify why "impulsive" is the most accurate term for actions driven by sudden inner impulses.