Pseudo-spikes on referential montage

There are various waves seen on referential montages that are easily mistaken for spikes. Consider the following:

Referential montage:

In the above, the wave at F7-M1-T3 between the eighth and ninth ECG beats resembles a spike. Notice that there is no following slow wave that is typical of a spike and slow wave. The wave is of opposite polarity at F8 and F7, M2 and M1, and T4 and T3, albeit subtly seen on the right. It is the subtlety of the discharge on the right that contributes substantially to the risk of calling this a spike. While the sharp component is negative, the slow drift of the eye following this is positive, indicating a leftward eye movement. In the prefrontal derivations, this is accompanied by an electro-negative discharge, indicating that the eye movements are leftward and downward (in other words, oblique). 

One can corroborate the above hypothesis by looking at the bipolar montages:

The same discharge on the bipolar anterior-posterior montage (above) is subtle; So subtle that, if you are reviewing on the latter montage, you would not even remotely consider this to represent a sharp wave.

The bottom line? Be cautious of sharply contoured waves, even those with a field identical to a temporal spike, on referential montages. The criterion of "a field" is insufficient to interpret a wave as representing a spike.