I can't speak for avast version 8.0 as I no longer have it installed, but that was certainly a part of the Quick and Full System Scans, see attached image of the Scan Now listing. Personally I would be looking at getting the latest avast version.
For avast 2014 9.0.2011
It isn't listed in the Quick scan settings, but it is in the Full System Scan.
I suggest that you don't modify the default Quick and Full System Scans, but create your own Custom scan.
I would also warn that doing a full memory scan (unlike that in the Full System Scan) is very likely to return some strange/unexpected results. You only have to browse the viruses and worms forum to see that.
As one of the senior avast team members has stated in the past, if there is a virus in memory, it is a bit late.