Advertisement Upgrade to remove ads

Group 1 in Willis and Schaie

Those who had been stable in their reasoning skills throughout the 14-year period had not experienced significant gains or losses.

Group 2 in Willis and Schaie

Those who had been deficient, through disease they had lost proficiency over the 14 year period.

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again


Reload the page to try again!


Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording