Numerosity representations in crows obey the Weber-Fechner law.

Area of Science:

• Comparative psychology
• Cognitive neuroscience
• Animal behavior

Background:

• Numerical estimation is common in animals, with primates showing consistent non-verbal numerical representations obeying the Weber-Fechner law.
• It remains unknown if vertebrates with different brain structures exhibit similar numerical discrimination abilities.

Purpose of the Study:

• To investigate numerical discrimination in carrion crows (Corvus corone) to determine if their performance mirrors that of primates.
• To explore the underlying mechanisms of numerical representation in birds.

Main Methods:

• Two carrion crows were tested on a delayed match-to-sample task involving numerosities from 1 to 30.
• Performance was analyzed for adherence to the Weber-Fechner law and the characteristics of their 'number line' representation.

Main Results:

• Crows demonstrated numerical discrimination based on an analogue number system, exhibiting the Weber-fraction signature.
• Their performance indicated that numerosity representations are scaled on a logarithmically compressed 'number line', similar to primates.

Conclusions:

• The findings suggest fundamentally similar number representations between birds and primates, challenging assumptions based on brain structure differences.
• This study supports the hypothesis of a logarithmic mental number line across vertebrates, resolving a classical psychophysics debate.