Full Breakdown
Crows Outpace Primates in Split-Second Visual Decisions
By Drooid · · How we work
Core Findings
Researchers trained two carrion crows (*Corvus corone*) on a random-dot motion discrimination task using a touchscreen. The birds pecked a target for a mealworm reward. Across thousands of trials the crows decided in an average of 235 ms, roughly twice as fast as response times reported for humans and non-human primates on comparable self-paced tasks. Neural recordings from the nidopallium caudolaterale (NCL) predicted the birds’ eventual choice as early as 70 ms after stimulus onset, about 170 ms before the peck. Accuracy remained high: with clear motion the crows approached 100 % correct, and even at 3 % coherent motion they performed above chance (? 50 %). Overall accuracy across the two individuals was ? 74 %.
Evolutionary Context
Crows belong to the corvid family, whose lineage diverged from mammals over 300 million years ago. Although birds lack a layered neocortex, the NCL functions analogously to the primate prefrontal cortex, supporting executive processes such as decision-making. The authors argue that the rapid computations illustrate convergent evolution of information-processing solutions across distinct brain architectures.
Neural Mechanisms
The NCL showed a gradual accumulation of sensory evidence, mirroring threshold-crossing dynamics described in primate prefrontal neurons. Early predictability (70 ms) suggests crows can compress visual information and reach a decision threshold faster than mammals, possibly because neural signals travel shorter distances in their compact, walnut-sized brains.
Data Summary
| Metric | Reported Value |
|---|---|
| Decision latency (behavior) | 235 ms (average) |
| Neural prediction onset | 70 ms after stimulus |
| High-coherence accuracy | ? 100 % |
| Low-coherence (3 % coherence) performance | ? 50 % correct |
| Overall task accuracy | ? 74 % |
| Number of recorded neurons | 248 in NCL |
| Sample size | 2 crows (Iggy and Lemmy) |
Official Statements & Responses
Andreas Nieder, comparative neuroscientist at the University of Tübingen, emphasized that the findings demonstrate sophisticated computation without a mammalian neocortex and linked the speed to ecological pressures of flight. Aaron Blaisdell, chair of behavioral neuroscience at UCLA, noted the consistency between the two subjects, suggesting the observed speed and accuracy reflect intrinsic biological capacity.
Conflicting Reports & Gaps
The study examined only two individuals and lacked a direct, side-by-side comparison with humans or monkeys on the identical task. Consequently, the “twice as fast” claim relies on prior literature rather than concurrent testing. The task assessed perceptual decision-making based on visual motion; other decision domains were not investigated, leaving open whether the speed advantage generalizes to broader cognitive contexts.
Verbatim Quotes
- “The bigger implication is that a brain does not need a mammalian neocortex to perform sophisticated computations,” — Andreas Nieder
- “Flight places enormous demands on visual processing and sensorimotor [sensation and movement] coordination,” — Andreas Nieder
- “It was nice to see that with a small-N study like this, they were able to get consistency between the two birds,” — Aaron Blaisdell