Various models have been developed to measure EI. The "trait model", developed by Konstantinos V. Petrides in 2001, focuses on self reporting of behavioral dispositions and perceived abilities. The "ability model", developed by Peter Salovey and John Mayer in 2004, focuses on the individual's ability to process emotional information and use it to navigate the social environment. Goleman's original model may now be considered a "mixed model" that combines what has since been modeled separately as "ability EI" and "trait EI". More recent research has focused on emotion recognition, which refers to the attribution of emotional states based on observations of visual and auditory nonverbal cues. In addition, neurological studies have sought to characterize the neural mechanisms of emotional intelligence.