 In research during later seasons of Sesame Street , verbal measurements , in the form of letter @-@ recognition tests , were introduced . These reinforced earlier results , providing more insight into children 's knowledge , reactions , and responses than behavioral measures alone . The distractor method was modified by Workshop researchers Lewis Bernstein and Valeria Lovelace into an " eyes @-@ on @-@ screen " method , which collected simultaneous data from larger groups of children . Their method also tested for more " natural " distractions , such as those provided by other children in group @-@ viewing situations ; up to 15 children were tested at a time . Lovelace developed additional testing methods , described by Fisch as " state @-@ of @-@ the @-@ art research design " . One innovation included the " engagement measure " , which recorded children 's active responses to an episode , such as laughing or dancing to music . 
