According to Erik Bleich, in his article "Defining and Researching Islamophobia", even when definitions are more specific, there is still significant variation in the precise formulations of Islamophobia. As with parallel concepts like homophobia or xenophobia, Islamophobia connotes a broader set of negative attitudes or emotions directed at individuals of groups because of perceived membership in a defined category. Mattias Gardell defines Islamophobia as "socially reproduced prejudices and aversion to Islam and Muslims, as well as actions and practices that attack, exclude or discriminate against persons on the basis that they are or perceived to be Muslim and be associated with Islam".