Now granted, one typically has a more positive association with summer rain than they do with a soiled diaper, but what I found so powerful was how the images triggered a sequence of internal events. The visual representation of the image triggered the memory of the object's smell, which triggered the physical reaction to the smell, which likely triggered some memories associated with the smells, which, in turn or in tandem triggered the emotion. At the conclusion of the film, I was left feeling the overall emotional state induced by the internal process described above, without a conscious awareness of the process itself.
In most cases, we all go through a similar, likely unconscious sequence of events when taking in a novel stimuli. What often remains of this process in our memories, however, is our emotional experience and not the object, memories or fears that may have triggered the emotions. Since this process often happens outside of our awareness, we often notice the resulting feeling state and mistakenly attribute the emotion to whatever happens to be in our conscious awareness at the time.
For example, let's say you find yourself tense, anxious and jittery one day at work and assume that you are really nervous about your upcoming presentation, causing you to perhaps doubt your presentation giving skills and perhaps even your job competence (a cognitive leap, for sure). Later in the day, however, your colleague points out that the two of you had recently discussed a particularly traumatic and threatening news article, that made her feel vigilant all day. Now perhaps because you were busy preparing for your presentation or because the article was too distressing to think about, you "forgot" about the distressing news but were left feeling quite anxious. In an effort to understand this feeling you searched your readily available surroundings and found the presentation that you were working on and assumed that you must be nervous and anxious about this, and went so far as to assume that your nervousness not only has to do with giving presentations but with your general inability to do your job well. In this instance, you went from feeling anxious about something that has little to do with you personally, to feeling insecure about your entire professional competence!
These types of misattribution errors are quite common and can cause significant distress, if the unconscious processes are not brought into conscious awareness. Whether you are able to stop yourself and examine your own process in the moment, or need an objective therapist to help you track your associations, attending to your unique physical, cognitive and emotional assumptions and reactions can be a wonderfully freeing and healing endeavor.