 In recent years there has been an explosion of work connecting semantics, reasoning, and cognition, much of it related to how speakers understand and learn and reason with quantified expressions. A major strand of research concerns monotonicity (section 13). Already Barwise and Cooper (1981) noted the ubiquity of monotone quantifiers in natural languages, and suggested a way of showing that monotone quantifiers are easier to process than non-monotone ones, and that increasing quantifiers are easier than decreasing ones. They also suggested that psychological experiments might be used to test their hypothesis. Their technical proposal was developed further in van Benthem (1986), which introduced a notion of count complexity and showed that, under some assumptions, the quantifiers with minimal count complexity are precisely the ones with a certain strong monotonicity  property.[39]