Acognitive psychologist studying different kinds of memory tasks who randomly assigns half of the participants to a recall condition and the other half to a recognition condition is conducting research.

The answer is "Experimental research".

Experimental research refers to any research led with a scientific approach, where an arrangement of variables are kept steady while the other arrangement of factors are being estimated as the subject of test.  

The most straightforward case of an experimental research is leading a laboratory  test. For whatever length of time that examination is being directed under logically satisfactory conditions – it qualifies as a trial explore. A genuine experimental research is thought to be fruitful just when the scientist affirms that an adjustment in the dependent variable is exclusively because of the control of the independent variable.

answer; the cats meowing will temporarily increase, but then it will decrease;