a small wearable recall device is provided to capture images triggered by a combination of a detection of a capture condition followed by a relatively stable period , as detected by an accelerometer . by triggering on the combination of a detected capture condition followed by a detected stability condition , a clearer image of the environment of an interesting event is expected to be captured . the small size of the recall device makes it possible to integrate it into common portable consumer products , such as mp3 players , purses , clothing , hats , backpacks , necklaces , collars , and other human - wearable products .