为图表添加背景色，我们可以使用'area'系列，
一种用于正色，一种用于负色.

to add background colors to the chart, we can use an 'area' series,
one for the positive color and one for the negative.

在加载初始数据后，
添加另外两列.
在图表的整个范围内为这些列添加行/值.
将null用作原始列值.

after the initial data has been loaded,
add two additional columns.
add rows / values for these columns for the full range of the chart.
use null for the original column value.

// add columns & rows for background
data.addColumn('number', '');
data.addRow([0, null, 8]);
data.addRow([-100, null, 8]);
data.addColumn('number', '');
data.addRow([0, null, null, 8]);
data.addRow([100, null, null, 8]);

在选项中，添加以下选项...

in the options, add the following options...

colors: ['blue', 'red', 'green'],  // colors for the series
lineWidth: 0,                      // remove line for top of area series
pointSize: 0,                      // remove points on area series
series: {                          // change last two series to area
  1: {type: 'area'},
  2: {type: 'area'}
}

然后放置图像标记时，忽略原始值为null的列.

then when placing the image markers, ignore columns where the original value is null.

  // exclude null values
  var yValue = data.getValue(i, 1);
  if (yValue !== null) {
    var xPos = layout.getXLocation(data.getValue(i, 0));
    ...

请参阅以下工作摘要...

see following working snippet...

google.charts.load('current', {
  packages: ['corechart']
}).then(function () {
  var data = new google.visualization.DataTable();
  data.addColumn('number', '');
  data.addColumn('number', '');
  data.addRows([
    [-0.5, 1],
    [100, 1],
    [-80, 2],
    [25, 2],
    [60, 8],
  ]);

  // add columns & rows for background
  data.addColumn('number', '');
  data.addRow([0, null, 8]);
  data.addRow([-100, null, 8]);
  data.addColumn('number', '');
  data.addRow([0, null, null, 8]);
  data.addRow([100, null, null, 8]);

  var options = {
    title: 'guilt experience Vs eat satisfaction',
    titlePosition: 'none',
    position: 'center',
    hAxis: {
      title: 'Guilt Value\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0\u00A0Eat Value',
      minValue: 0,
      maxValue: 15,
      ticks: [0, 20, 40, 60, 80, 100, -20, -40, -60, -80, -100]
    },
    vAxis: {
      title: '',
      minValue: 0,
      ticks: [0, 1, 2, 3, 4, 5, 6, 7, 8]
    },
    legend: {
      position: 'none'
    },
    colors: ['blue', 'red', 'green'],
    lineWidth: 0,
    pointSize: 0,
    series: {
      1: {type: 'area'},
      2: {type: 'area'}
    }
  };

  var container = document.getElementById('chart_div');
  var chart = new google.visualization.ScatterChart(document.getElementById('chart_div'));

  google.visualization.events.addListener(chart, 'ready', function() {
    var layout = chart.getChartLayoutInterface();
    for (var i = -0; i < data.getNumberOfRows(); i++) {
      // exclude null values
      var yValue = data.getValue(i, 1);
      if (yValue !== null) {
        var xPos = layout.getXLocation(data.getValue(i, 0));
        var yPos = layout.getYLocation(yValue);
        var whiteHat = container.appendChild(document.createElement('img'));
        if (data.getValue(i, 0) < 0) {
          whiteHat.src = 'https://i.imgur.com/LqiTeQI.png';
        } else {
          whiteHat.src = 'https://i.imgur.com/rACTObW.png';
        }
        whiteHat.style.position = 'absolute';
        whiteHat.style.height = '15px';
        whiteHat.style.width = '15px';
        whiteHat.style.top = (yPos) + 'px';
        whiteHat.style.left = (xPos) + 'px';
      }
    }
  });
  chart.draw(data, options);
});

<script src="https://www.gstatic.com/charts/loader.js"></script>
<div id="chart_div"></div>