Final answer:
The missing element in the Interpersonal Communication Model is feedback. Feedback allows the receiver to indicate understanding or prompt additional communication. Encoding is the conversion of information into symbols, and decoding is interpreting these symbols.
Step-by-step explanation:
The Interpersonal Communication Model includes various elements: the environment, the sender, the receiver, the message, the channel, and the missing element from the provided options is feedback. Feedback is crucial as it indicates that the receiver has understood the message, or it may signal confusion or a misunderstanding, prompting further communication to clarify the message.
Even in the case of long-distance communication in the human body, the nervous system and endocrine system maintain control and coordination through the transmission of signals (messages). The process of encoding a message involves converting thoughts or information into a symbolic form that can be communicated.
While decoding is the reverse process, where the receiver interprets the sender's message. Concerning the possibility of recognizing a message from an alien species, it suggests that communication may also depend on the ability to recognize and interpret unexpected forms of signals.