What paiting technique builds up oil paint to create more 3d effect?

I have a 40 year old oil painting where the artist adds gobs of extra paint to various items within a still life painting to create a more three dimensional effect. The items in my painting is some pieces of fruit in the foreground. The paint is probably 1/4 inch thick in these places. What is this method called? The method probably uses a palette knife.What paiting technique builds up oil paint to create more 3d effect?
Add Gel Medium to your oil paints. The more you add the thicker the paint.