When Prophet Muhammad compared men and women as follows in one of the hadith, which says women are weaker in reason and religious. While it is difficult to understand deficiency in religion I would like to know more about deficiency in reason.
"I have not seen anyone more deficient in ability to reason and deen than you. A cautious sensible man can be led astray by some of you.” It was said: “O Allah’s Messenger (peace be upon him)! What is the deficiency in our reasoning and deen?” He said: “Is not the testimony of two women equal to the witness of one man?” It was said: "What is deficient in her deen?" The Prophet (peace be upon him) said: "Is not it true that a woman can neither pray nor fast during her menses?” [Al-Bukhari]
Are there studies which can prove or disprove this claim?