A frame that to explain any blinding procedures to parents, and offer them the option to preview stimuli before the study. Two buttons allow the user to move forward: one goes to the next frame (if the parent wants to preview stimuli), and one skips the next frame and goes to the one after that (if the parent declins). Therefore, this frame should be followed by an ExpVideoPreview frame.

"frames": {
   "my-video-preview-explanation": {
       "introBlock": {
           "text": "During the videos, we'll ask that you hold your child over your shoulder like this, so that you're facing face away from the screen."
       },
       "image": {
           "alt": "Father holding child looking over his shoulder",
           "src": "https://s3.amazonaws.com/lookitcontents/exp-physics/OverShoulder.jpg"
       },
       "kind": "exp-lookit-preview-explanation",
       "skipButtonText": "Skip preview",
       "previewButtonText": "I'd like to preview the videos",
       "id": "video-preview-explanation",
       "blocks": [
           {
               "text": "The reason we ask this is that your child is learning from you all the time. Even if he or she can't see where you're looking, you may unconsciously shift towards one side or the other and influence your child's attention. We want to make sure we're measuring your child's preferences, not yours!"
           },
           {
               "text": "If you'd like to see the videos your child will be shown, you can take a look ahead of time now. It's important that you preview the videos without your child, so that the videos will still be new to them."
           }
       ],
       "showPreviousButton": true
   }
}