Consciousness in dolphins? A review of recent evidence

Heidi E. Harley

For millennia, dolphins have intrigued humans. Scientific study has confirmed that bottlenose dolphins are large-brained, highly social mammals with an extended developmental period, flexible cognitive capacities, and powerful acoustic abilities including a sophisticated echolocation system. These findings have led some to ask if dolphins experience aspects of consciousness. Recent investigations targeting self-recognition/self-awareness and metacognition, constructs tied to consciousness on some accounts, have analyzed the dolphin's ability to recognize itself in a mirror or on a video as well as to monitor its own knowledge in a perceptual categorization task. The current article reviews this work with dolphins and grapples with some of the challenges in designing, conducting, and interpreting these studies as well as with general issues related to studying consciousness in animals. The existing evidence does not provide a convincing case for consciousness in dolphins. For productive scientific work on consciousness in dolphins (and other animals including humans), we need clearer characterizations of consciousness, better methods for studying it, and appropriate paradigms for interpreting outcomes. A current focus on metamemory in animals offers promise for future discovery in this area.