diff --git a/test/api/v3/integration/user/auth/POST-register_local.test.js b/test/api/v3/integration/user/auth/POST-register_local.test.js
index 0a86f10daf..e41cf27a69 100644
--- a/test/api/v3/integration/user/auth/POST-register_local.test.js
+++ b/test/api/v3/integration/user/auth/POST-register_local.test.js
@@ -66,6 +66,7 @@ describe('POST /user/auth/local/register', () => {
       });
 
       await expect(getProperty('users', user._id, '_ABtest')).to.eventually.be.a('string');
+      await expect(getProperty('users', user._id, '_ABtests')).to.eventually.be.a('object');
     });
 
     it('requires password and confirmPassword to match', async () => {
diff --git a/website/server/libs/analyticsService.js b/website/server/libs/analyticsService.js
index 1e29eaea80..5e3b16d38e 100644
--- a/website/server/libs/analyticsService.js
+++ b/website/server/libs/analyticsService.js
@@ -7,6 +7,7 @@ import useragent from 'useragent';
 import {
   each,
   omit,
+  toArray,
 } from 'lodash';
 import { content as Content } from '../../common';
 
@@ -90,6 +91,9 @@ let _formatUserData = (user) => {
   if (user._ABtest) {
     properties.ABtest = user._ABtest;
   }
+  if (user._ABtests) {
+    properties.ABtests = toArray(user._ABtests);
+  }
 
   if (user.registeredThrough) {
     properties.registeredPlatform = user.registeredThrough;
diff --git a/website/server/libs/cron.js b/website/server/libs/cron.js
index fb99b88290..a7f03c096a 100644
--- a/website/server/libs/cron.js
+++ b/website/server/libs/cron.js
@@ -130,6 +130,8 @@ function trackCronAnalytics (analytics, user, _progress, options) {
 
 function awardLoginIncentives (user) {
   if (user.loginIncentives > 50) return;
+  // A/B test 2016-12-21: Should we deliver notifications for upcoming incentives on days when users don't receive rewards?
+  if (!loginIncentives[user.loginIncentives].rewardKey && user._ABtests && user._ABtests.checkInModals === '20161221_noCheckInPreviews') return;
 
   //  Remove old notifications if they exists
   user.notifications
diff --git a/website/server/models/user/hooks.js b/website/server/models/user/hooks.js
index 5e0f04d80e..a651c55ad4 100644
--- a/website/server/models/user/hooks.js
+++ b/website/server/models/user/hooks.js
@@ -10,7 +10,7 @@ import schema from './schema';
 schema.plugin(baseModel, {
   // noSet is not used as updating uses a whitelist and creating only accepts specific params (password, email, username, ...)
   noSet: [],
-  private: ['auth.local.hashed_password', 'auth.local.salt', '_cronSignature', '_ABtest'],
+  private: ['auth.local.hashed_password', 'auth.local.salt', '_cronSignature', '_ABtest', '_ABtests'],
   toJSONTransform: function userToJSON (plainObj, originalDoc) {
     plainObj._tmp = originalDoc._tmp; // be sure to send down drop notifs
     delete plainObj.filters;
@@ -78,6 +78,12 @@ function _setUpNewUser (user) {
   let iterableFlags = user.flags.toObject();
 
   user._ABtest = '';
+  // A/B test 2016-12-21: Should we deliver notifications for upcoming incentives on days when users don't receive rewards?
+  if (Math.random() < 0.5) {
+    user._ABtests.checkInModals = '20161221_noCheckInPreviews'; // no 'preview' check-in modals
+  } else {
+    user._ABtests.checkInModals = '20161221_showCheckInPreviews'; // show 'preview' check-in modals
+  }
   user.items.quests.dustbunnies = 1;
 
   if (user.registeredThrough === 'habitica-web' || user.registeredThrough === 'habitica-android') {
diff --git a/website/server/models/user/schema.js b/website/server/models/user/schema.js
index 2d33d822f6..dd1b3f9a1a 100644
--- a/website/server/models/user/schema.js
+++ b/website/server/models/user/schema.js
@@ -527,7 +527,10 @@ let schema = new Schema({
     return {};
   }},
   pushDevices: [PushDeviceSchema],
-  _ABtest: {type: String},
+  _ABtest: {type: String}, // deprecated. Superseded by _ABtests
+  _ABtests: {type: Schema.Types.Mixed, default: () => {
+    return {};
+  }},
   webhooks: [WebhookSchema],
   loginIncentives: {type: Number, default: 0},
 }, {