P300 is seen for both frequent and infrequent stimuli. As a motor response is expected for infrequent stimulus, sometimes it is hard to distinguish P300 from the mu response. See for more information about P300 with target and non-target stimulus. Katayama, J. I., & Polich, J. (1998). Stimulus context determines P3a and P3b. Psychophysiology, 35(1), 23-33.

As suggested by Pragati, P300 is indeed seen in complex stimulus setups as well. Even if you have an anticipatory motor response or not. Salisbury et al (2001) have argued that motor responses do have an effect on P3 response amplitude. 

There are plenty of studies showing P3 responses to tri-tone stimulus setups, for instance, S1 is standard, S2 is a distractor and S3 is the target. This can be viewed from the perspective of relevance detection. Omitted P3 is common too. A good starting point is Polich (2007). 

Best,

Kanad 

Pragathi di... Nice to hear from ur side... I m aware of the P300 with the three stimulus odd ball paradigm as said in the reference u cited...as Mandke suggested ample of literature evidence on standard, one target and a distractor (as in  p3a, p3b paradigm) is available.... But my doubt is can one elicit P300 for multiple targets (say 3 targets and one standard) 

I am sure you can elicit a P3-like response from 3 targets but I am not sure what you're trying to address using such a paradigm. Having said that, this can be achieved on one condition; that all the targets are 'novel' and they're not repeated in a sequence. As repetition of the same stimulus will diminish the response. The way to understand the paradigm would be as follows: 

The P3 reflects cortical activity related to on going processing of task relevant stimuli. Once the early sensory evaluation of the stimulus is complete, in the late latency window; there is an active comparison between the sensory trace of the former stimulus and the new/novel incoming stimulus. This is the key process that I think, differentiates the mismatch response and P3. Now, if no stimulus related or task related change is detected then the sensory trace is maintained, as a consequences you will record evoked potentials that are lower in hierarchy, i.e., N1/P2 etc. In other words, higher is the novelty, better is the response. So the entire emphasis will be on the experimental design. 

Kanad 

Hi Kanad Mandke, 

I think you are right the procedure of eliciting P300 for 3 different deviants. I in the odd-ball paradigm should be very strictly made. No two different deviants should not be repeated one-after the other.

As you are going to have 3 different deviants. The P300 should be better over the one deviant condition. Because, I guesses that the memory trace for each deviant would be week, that is because time laps is larger in 3 deviant than one deviant condition for each deviant. So week memory trace for deviant would elicit a better P300. It will also be interesting to look at if two deviants are repeating one-after the other.