Why am I getting [object Object] printed to the screen and not its actual contents?

Question

I'm having trouble with this search function that I'm working on. I (think I) am passing the contents of an array of objects onto a var contactList and then print that to the webpage. Instead, what I'm getting is:

Here is part the search function of my js file as well as my html.

function doSearch()
{
    readCookie();
    accessIdForEdit = "";
    var lookUp = document.getElementById("searchText").value;
    document.getElementById("contactSearchResult").innerHTML = "";
    var searchList = "";

    var jsonPayload = JSON.stringify({search:lookUp, userId:userId});
    var url = urlBase + '/LAMPAPI/search.' + extension;
    var xhr = new XMLHttpRequest();

    xhr.open("POST", url, true);
    xhr.setRequestHeader("Content-type", "application/json; charset=UTF-8");
    try {
        xhr.onreadystatechange = function () {
            if (this.readyState === 4 && this.status === 200) {

                document.getElementById("contactSearchResult").innerHTML = "Search has been retrieved";
                var jsonObject = JSON.parse(xhr.responseText);

                for( var i=0; i<jsonObject.results.length; i++ )
                {
                    searchList += jsonObject.results[i];
                    if( i < jsonObject.results.length - 1 )
                    {
                        searchList += "<br />\r\n";
                    }
                }

                document.getElementsByTagName("p")[0].innerHTML = searchList;

            }
        };
        xhr.send(jsonPayload);
    }
    catch(err)
    {
        document.getElementById("contactSearchResult").innerHTML = err.message;
    }
}

<div id = "contactSearchDiv" style = "display: none">
    <input type="text" id="searchText" placeholder="Contacts To Search For"/>
    <button type="button" id="confirmSearchButton" style="display:block" onclick="doSearch();"> Search </button></br>
    <button type="button" id="returnFromSearch" style="display:block" onclick="displayChange('mainPanel', 'contactSearchDiv');">
        Return to Page </button><br/>
    <span id="contactSearchResult"></span>
    <p id="searchList">
    </p><br /><br/>
</div>