Final answer:
After Iris sustains frontal lobe damage, his friends and family will mostly likely observe an increase in impulsivity and difficulties with impulse control, based on the functions of the prefrontal cortex and similar cases such as Josephine Gage.
Step-by-step explanation:
According to the lecture "Brain and Hormones," after Iris is shot in the head and sustains damage only to his frontal lobe, his friends and family will MOST likely notice a change characterised by c) impulsivity and difficulty with impulse control. This prediction is based on what is known about the functions of the prefrontal cortex and the associated case study of Josephine Gage, which illustrates how an injury to this region can lead to profound personality changes, including loss of impulse control and alterations in social behaviour.
Damage to the frontal lobe, specifically the prefrontal cortex, is correlated with diverse behavioural symptoms such as changes in personality, mood swings, and lack of judgement. The case of Josephine Gage exemplifies these effects as he experienced significant personality changes after an iron rod impaled his prefrontal cortex. These changes encompassed becoming more irritable, temperamental, and having problems with impulse control—which are typical symptoms associated with frontal lobe damage.
Other cognitive and emotional functions, such as planning, reasoning, and working memory, which are also housed within the prefrontal cortex, may be impacted. This can result in an individual experiencing a shift in their personality, demonstrating behaviours such as impulsive decisions and erratic mood changes, which were not present before the incident.