Change image title on mouse over event using java

Hello,

I am extremely new to Java and I was just wondering if there is some simple command that will change the title of an image on a mouse over event. I have a small script worked out that changes the image src on a mouseover but I haven't been able to figure out a way to change the title of the image as well. My script is as follows:
<script language="JavaScript">

var ResearcherImage = new Array();
var ResearcherText = new Array();

ResearcherImage[0] = "Images/Button.gif";
ResearcherImage[1] = "Images/Clear_Button.gif";

ResearcherText[0] = "Button Image";
ResearcherText[1] = "Clear Button Image";

function changeImage(whichImage)
{
if (document.body)
{
document.images["Researcher"].src = ResearcherImage[whichImage]; **Researcher is the name of the image**
}
}
</script>

The html code for the link is:
<td id="grey_links"><a href="#" onMouseOver="javascript:changeImage(0)">Change</a></td>

The html for the img that is being altered is:
<img src="Images/Biography.gif" name="Researcher" title="" />

Thanks

 

use
<img src="image.gif" onmouseover="this.title='title1'" onmouseout="this.title='title2'" >