From LimeSurvey Manual
Text inputs (input_boxes)
It is available only for the Array (Numbers) question type.
The answer has to be typed within a text box if this option is enabled. The step value will not be used. The respondents can submit a numerical value as answer.
Otherwise, the survey participants will have to choose from a dropdown list the answer option to the question.
- On - the input box is used
- Off (default) - the dropdown list is used