History has revealed time and time again that science is moved forward by revolutions that pit one point of view, theory, or methodology, against an opposing view. During calmer times, however, we as researchers are left to our own devices and settle into our work with little thought to the world around us. The field of learning and memory has been privy to many such revolutions in the past but has yet to form a cohesive, modern message. Grau and Joynes suggest that our strong ties to the past are to blame for a lack of progression in the field. We agree and add that the focus of the field on two extreme ends of a continuum has also held us back; suggesting that research that goes on in the middle of the continuum may be the key to leading the field out of its rut.

In a previous study, a latent inhibition (LI) effect was found to be dictated by a facilitation of the acquisition of a conditioned eyeblink response in context pre-exposed rabbits as opposed to slower learning in tone preexposed rabbits. In the present experiments, we examined the effects of preexposure to the tone conditional stimulus (CS) using a similar paradigm with rats. In Experiment 1, rats were given four or eight days of context (SIT) or CS preexposure (TONE) followed by eight days of paired training. Unlike rabbits, control and eight day SIT groups learned faster than TONE exposed rats and the four day SIT group. In Experiment 2, we controlled for the context preexposure control rats received during adaptation in Experiment 1 and tested rats given two days of CS preexposure or no preexposure. Again, SIT rats learned faster than TONE rats as well as rats that did not receive any preexposure. In Experiment 3, we tested a frequently-used method for examining LI, whereby paired training began immediately after the last of four sessions of preexposure, but observed no effect. Similar to our previous results, any LI effect produced in the present set of experiments arose from facilitated performance by SIT rats as opposed to deficits in learning in TONE rats. The present results highlight the need for a unifying theory of preexposure effects immune to differences experimental paradigms and parameters in order explain the variety of results obtained in the field.