Blocking in the spatial domain with arrays of discrete landmarks

A characteristic feature of associative conditioning is that learning a pre dictive relationship between two events can block later learning about an a dded event. It is nor yet well established whether blocking occurs in the s patial domain or the circumstances in which it does. We now report, using r ats trained to search for hidden food near landmarks in an open held arena, that blocking can occur in spatial learning. The animals noticed the added landmark at the start of the blocking phase and explored it, but either fa iled to incorporate it into their spatial map or developed a representation in which only some landmarks actually control behavior. Additionally, perf ormance at asymptote was controlled by the shape of the landmark array rath er than the individual landmarks comprising it, indicating that blocking in the spatial domain may represent a failure to alter the encoded geometry o f a learned array.