Final answer:
An operation on Kiara's frontal lobe would likely result in impaired decision-making and judgment due to the role of the frontal lobe in executive functions and personality.
Step-by-step explanation:
The frontal lobe is critical for several aspects of cognition and behavior, including decision-making, judgment, planning, and emotional regulation. Following an operation by aliens on Kiara's frontal lobe as stated in the hypothetical scenario, the behavioral change that her friends and family would most likely notice is impaired decision-making and judgment. This is because the frontal lobe, particularly the prefrontal cortex, is responsible for executive functions such as planning, self-control, and abstract thought. As seen in historical cases like Phineas Gage, and supported by neuroscientific research, damage to the frontal lobe can result in personality changes, poor judgment, difficulty with planning and executing tasks, as well as problems with impulse control and mood regulation.