As in first language acquisition, cognitive and developmental psychologists argue that there is no need to hypothesize that humans have a language-specific module in the brain or that 'acquisition' and 'learning' are distinct mental processes. In their view, general theories of learning can account for the gradual development of complex syntax and for learners' inability to spontaneously use everything they know about a language at a given time. As noted above, some linguists have also concluded that, while UG provides a plausible explanation for first language acquisition, something else is required for second language acquisition since it so often falls short of full success.