> For the complete documentation index, see [llms.txt](https://ldevumd.gitbook.io/bittsy/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ldevumd.gitbook.io/bittsy/goals-and-capabilities/paradigms/preferential-looking-procedure.md).

# Preferential Looking Procedure

In addition to HPP, BITTSy also allows testing using the Preferential Looking Paradigm (Golinkoff, Ma, Song, & Hirsh-Pasek, 2013). During this procedure, children are presented with pairs of images (or animated objects) on a screen. This can include familiar (e.g., a hand) or unfamiliar items (e.g., an object that the child would not know the label for). Sometimes the objects are presented one at a time (e.g., during familiarization and training), and sometimes they appear in pairs or in groups of 4 images. Images are accompanied by speech stimuli, which may include sentences either teaching children a new word, or instructing them to look at one of the objects on the screen. A digital camera positioned near the screen (typically above or below) records children’s eye movements. Videos of the test-sessions are then coded off-line on a frame-by-frame basis by trained research assistants, to measure participants' fixations and to calculate accuracy and reaction times across trials.