Perceiving complex causation through interaction

When we interact with a touch screen computational device we have the strong subjective impression that we are directly causing changes that occur on the screen. For example, sliding a finger on a screen causes scrolling of the information. But the current method for showing causal relationships derived from models is to use a causal network diagram with nodes representing entities and arrows represent causal relationships between those entities. Sometimes arrows are labeled to weight the connections. In such diagrams there is no immediate visual impression of causal links, just the perception of connections and the arrowhead symbol. Interactive touch screens would seem to offer the potential for creating interactive diagrams where the causal relationships are provided in a perceptually immediate and unequivocal fashion. This paper explores methods for creating interactive diagrams using multiple touches that go beyond simple positive causation to express complexities such as causal effect enhancement, causal effect reduction and causal effect blocking. A design rationale is presented with special attention to temporal constraints. Results from an evaluation study suggest that the design can be understood with minimal instruction by most people.