public void showMainInstructions(final int pageIndex) {
		removeActionListeners(nextButton);
		removeActionListeners(previousButton);
		
		if (pageIndex < Text.TEXT_INSTRUCTIONS.length) { 
			//not last page
			nextButton.setText(Text.BTN_NEXT);
			nextButton.setVisible(true);
			nextButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent arg0) { //on click, close the gui		
				showMainInstructions(pageIndex + 1);
			}});
		} 
		
		if (pageIndex > 1) { 
			//not first page
			previousButton.setText(Text.BTN_PREVIOUS);
			previousButton.setVisible(true);
			previousButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent arg0) { //on click, close the gui		
				showMainInstructions(pageIndex - 1);
			}});
		} else {
			previousButton.setVisible(false);
		}
		
		if (pageIndex == Text.TEXT_INSTRUCTIONS.length) { 
			//last page			
			nextButton.setText(Text.BTN_BEGIN);
			nextButton.setVisible(true);
			nextButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent arg0) { //on click, close the gui		
				previousButton.setVisible(false);
				nextButton.setVisible(false);
				Experiment.xp.displayAndContinue(); 
			}});
		}				
		setInstructions(Text.TEXT_INSTRUCTIONS[pageIndex - 1]);		
	}