Figure 52: Voluntary retraction of the lower lip 1854 - 1856

Guillaume Duchenne de Boulogne was a neurologist known for his pioneering studies in facial expressions. This photograph, titled "Figure 52: Voluntary Retraction of the Lower Lip", is part of his 1862 book *Mécanisme de la Physionomie Humaine*. Duchenne used electrical stimulation to induce specific facial expressions in his subjects, documenting them through photography. This particular image depicts a man with a forced smile, capturing the exaggerated contraction of the muscles around the mouth. This image is considered to be an important historical document, offering valuable insights into the scientific study of human expression.