listToVisibleChange.js

var myConditionalLogicController = Marionette.Object.extend({
    
    initialize: function () {
        
      this.listenTo( Backbone.Radio.channel('fields'), 'change:model', this.fieldModelChange );
    },
    
    fieldModelChange: function( fieldModel ) {

        if ( fieldModel.changed.visible !== true) return;
        
        // code to be run when a conditional is field is shown

    }
});