Associations and Conditioning

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Imagine that I write:
Her face was shaped like a strawberry.
Even though I'm only referring the reader to the shape of the strawberry, I'm certain that the reader will also take other characteristics from their strawberry template. Maybe just the dominant ones, such as the smell of the strawberry and/or the taste of the strawberry (and perhaps PRS plays a big part here)? There might even be readers who have had unpleasant strawberry experiences and transpose these onto my girl and/or her face.
How was it for you?
Maggot Farm is a good example. I instantly imagine the smell and need no coercing to do this. See how easily we can make the reader smell something pleasant without actually mentioning smell at all:
Her dress was the colour of roses.
Or an unpleasant smell:
Her dress was the colour of rotten eggs.
So, while we're describing one thing, we can be pretty sure that the reader is taking a lot more from the words and, with practise, we can fill every paragraph with subliminal references.

Note that we can condition the reader to respond to certain trigger words.
A great and very simple example of this is the movie Silent Hill.
The protag hears the siren and then the darkness descends and monsters appear.
The next time we hear the siren, we fear the worst, and the worst is delivered.
We are conditioned to associate terrible things with the siren.

How easily can we do this?
In a short backstory, I recount Corus' mother's last few months. Rather than telling the reader that she lost control of her bowels, I show this, and each morning Corus hangs freshly washed bedsheets and pillow cases, and they billow in the wind, over the strawberry nets. (I remember, as a kid, tunneling under my Nan's strawberry nets to retrieve strawberries.)
Further to this, Corus ends his mother's suffering and euthenizes her with a pillow.
Now I have created associations: each time I mention the word strawberry or the word pillow, the reader (hopefully) is reminded of the event and (even more hopefully) of Corus' terrible dilemma and his guilt and pain.
I am free to remind the reader of Corus' anguish at the drop of a strawberry or pillow, and the reader knows what Corus is thinking when his life model presents him with a strawberry and when he is setting up the pillows in readiness for her first pose.
In this way, I can (very hopefully) insert sympathy into any scene with a single word.

Repetition plays a part here, working as a reinforcer. The value of repetition has long since bugged me, and I'm starting to find a good few beneficial uses.
One technique I use with great relish is to create theme sets. If, for example, I want my reader to feel, totally without knowing why they feel it, that my protag is about to be tortured, I can introduce a set of words that refer to torture. In the context of the narrative, and taken in isolation, they will probably not be read that way, but when this theme is reinforced again and again, the impression is made. Indeed, I am frequently told that I leave people with peculiar feelings.
So, I'll build a list of words that relate to torture. I usually create lists of around thirty words. And then I'll slot these into the narrative, and I can do this totally irrespective of what is going on in my story. Now my protag walks past slices of cliff and the trees have turned into pines spread with needles, piercing the sky and the sun cauterizes shadows upon the burning sand and so forth. And a brilliant side-effect of these theme sets is that imaginative prose (N400) is unleashed.