interestedness

However, through all the rigid discipline the little girl retained her natural buoyancy of childhood, the spontaneous interestedness, the cheerfulness and animation, which were a part of her goodly heritage.

From Patchwork A Story of 'The Plain People' by Helen Mason Groce

I think it was the clearness and understanding in them, and a sort of great interestedness.

From The White People by Frances Hodgson Burnett

Now that Roxalanne came to entreat him to do that which already he saw himself forced to do, he turned his attention to the profit that he might derive from her interestedness on my behalf.

From Bardelys the Magnificent; being an account of the strange wooing pursued by the Sieur Marcel de Saint-Pol, marquis of Bardelys... by Rafael Sabatini

We are told that Matthew Arnold combined all the characteristics of good conversation—politeness, vivacity, sympathy, interestedness, geniality, a happy choice of words, and a never-failing humor.

From Talks on Talking by Grenville Kleiser

"Take into account the skill of forgers and the interestedness of apologists and calumniators."

From Bouvard and Pécuchet A Tragi-comic Novel of Bourgeois Life by Gustave Flaubert