how to use dependent set a value

editor1.dependent( 'option', function ( val )
{
if (val === 'value1' || val === 'value2')
{
return {show: ['field1', 'field2', 'field3']};
}
else
{
return {hide: ['field1', 'field2', 'field3']};
}
} );

in the code above I need to set a specific value to field1 how can I do?
Sam