In this context, the contact is assumed to be physical. But, the contact can just be a glance, and the trace is in your memory.
Many years before Will & Grace, there was a series called Dharma & Greg. The show was a US comedy, and got little coverage in the UK. I only saw it once or twice, I was on night shift and viewing was hard.
Years later, Criminal Minds became a big hit and got a lot of UK coverage. Within minutes of seeing the first show, I recognised the head of the unit. At first I didn't know from where, but my family never doubted I was right. My memory for faces from TV & Cinema is almost infallible. The man turned out to be Gregg. I hadn't seen him between the series, so, I had not been able to form a good link.
D&G was before W&G, and W&G ran for several years. This shows the powerfulness of memory. Locard's laws of exchange, I only saw the programme a few times. But, it left a trace in my mind.
To end, man is an existential being. Unless you live in a remote cave and forbid contact of any kind. Your consciousness will absorb outside influences, even if you don't think it does.