Yes I concur, in both examples the rhythm guitar is using a wah wah pedal.
Let's explore this a little further. The early versions of the wah wah pedal used a filter to make variations in the peak response frequency of the guitar input depending on where the pedal was positioned. Rocking the pedal back and forth opens and closes this filter response. Now a days you can find many effect pedals with an automated version of the wah effect by driving the filter with an adjustable variable speed oscillator.
There is considerable technique in using a wah wah pedal and some brands are favored over others. Good technique is more than merely rocking the pedal back and forth, it has to do with timing and where the musician places the upper and lower bound of the pedal excursion that creates the right effect for the song. This effect pedal is likely one of the most expressive of all the effects because it allows for human touch while playing albeit it is usually a foot. You should also take a look at Peter Frampton's talk box which is a close relative to the wha wha effect.
As sited in this wiki article "Chet Atkins had used a similar, self-designed device on his late 1950's recordings of "Hot Toddy" and Slinkey."
However, the most notable examples came late in the 1960's with Cream's "White Room", Jimi Hendrix's "Voodoo Child (Slight Return)".
If one searches long enough you might find some non main stream electronic music wizard doing something similar before Atkins with using manually controlled filters and any of a variety of audio sources.