Complex sentence: One of the main picture arrangement subtests used today is in The Wechslers Adult Intelligence Scale (WAIS) which is an individually based test that tests the intelligence or IQ of the person taking the test.
Split into simpler sentences: One of the main picture arrangement subtests used today is in the Wechslers Adult Intelligence Scale (WAIS). This is an individually based test that tests the intelligence or IQ of the person taking the test.