The experiments outlined in the above empirical provided a glimpse at various facets of the Temporal Binding phenomenon, and yet several questions remain. Firstly, the Magnitude Estimation paradigm of Experiments 1 -5 will most likely be of great use for the future investigation of the Temporal Binding phenomenon. In the studies outlined in the above Empirical Sections I attempted to investigate a binding between intentional causal actions and their subsequent effects, however the question remains whether Binding is a low-level process that modifies Intentional/Causal action effect
sequences based their likely temporal closeness, or whether this process employs higher level concepts that contain real world time-frame information. The TMS results of Haggard and Clark (2003) to some degree suggests that Binding is capable of more than a simple attraction effect by demonstrating a repulsion of the reported onset of action and effect when the action is involuntary. Whilst previous research has indicated that a complex higher level understanding of the relationship between events had been shown to mediate the reported causal relationship between the two (e.g. Buehner & May, 2004) it remains to be seen whether an understanding of such relationships can mediate the direction of a temporal shift, possibly by either slowing down or increasing the SET pacemaker speed.
The previous experiments reported here and those outlined in the Introduction tend to involve somewhat abstract button press electronic tone sequences in which participants may not be aware of the relationship between the two. It is logical to assume that most if not all participants have some form of experience with similar electronic relationships where an action (e.g. keyboard press, mouse click) results in a relatively sudden response (such as a document opening or a sound file playing), and given the electronic nature of these experimental action-effect relationships an assumption may be that the button presses ought to result in an immediate or near immediate effect. In this case a shortening of the inter-event interval would appear to be the best course of action in terms o f the intention/causality based Binding process. However, suppose that participants were aware that the action effect sequence involved some form of mechanical action that tended to take a longer period of time to resolve? At that point a shortening of the reported action event sequence would to some degree be detrimental to the causal inference as it would violate the expected relationship between the two events. Instead, a lengthening of this reported relationship would better
reflect the higher-level conceptualization of the temporal relationship. In this case, whilst giving the participants some form of cover story in the Libet clock paradigm may be of interest, the Magnitude Estimation and Reproduction paradigms offers the chance to implicitly and explicitly manipulate the expected action effect sequence between two abstract stimuli with the use of cover stories that identify these stimuli in terms of real world objects. For example the comparison of the interval between changes in the appearance of two onscreen shapes (assuming that the Binding process employs higher order relations) would result in shorter estimates of the duration (relative to changes in unrelated stimuli) when participants expected that a change in one would result in a quick change in the other when implied by a cover story. However, should this story imply a longer (e.g. mechanical) relationship, then arguably the same interval could be reported as longer to reflect this expected temporal relation.
In terms of identifying the underlying Causal or Intentional nature of the Binding effect in the above Empirical Sections I demonstrated that the effect does not occur in the absence of a Causal relationship (see Experiments 8-9). However, as of now I can only state that causality in the presence of an intentional action is required to demonstrate a Binding effect, and cannot as yet say whether it occurs independently of intentional action. Indeed, Moore and colleagues (2009) have demonstrated the importance o f contingency in pre and postdictive Temporal Binding shifts, while stating categorically that these results do not mean that motor signals have no influence on the experience of action.
A new series of experiments is required to comprehensively answer this question, by removing intentionality from the action-effect relationship. Take for example a device that pushes a button after a random interval, and this button press then causes a tone. This would completely remove intentionality from the button press-effect
relationship, as the machine itself would not have an intentional state. However, the button press and resultant tone would still be causally related, and a Causal Binding explanation predicts a reported shortening of the interval between cause and effect in this case, despite the absence of an intentional agent. While previous studies have done something similar to this (Wohlschlager, Engbert, & Haggard, 2003; Wohlschlager, Haggard, Gesierich, & Prinz, 2003) I argued in the Introduction that these non- intentional relationships, such as a self depressing key, may not be considered as causing the tone. Rather both key depression and tone may be considered as resulting from unseen cause, such as a computer program. The above device would provide a more explicit cause-effect sequence than these studies, as the lever hitting a button would cause the tone, and participants would be required to judge the interval between these events.
Such a device could quite easily be used in a Magnitude Estimation experiment (such as Experiments 1-5), as well as a Reproduction experiment (Experiment 6). In both cases one would predict that if Intentional action (in the presence of a Causal relationship) is required for the manifestation of the Binding shift, then the reported inter-event intervals would not be significantly different form a superficially similar Non-Intentional/Non-Causal event sequence given that neither condition involves an intentional agent. However, should causal beliefs underpin the Binding process, then due to the causal relationship between button press and effect, participants should rate the button press resulting from the device’s action and the subsequent caused tone (Causal/Non-Intentional sequence) as shorter than a similar unrelated event sequence. Moving towards the empirical origins of Temporal Binding, the application of such a device to Haggard, et al.’s (2002a) original Libet Clock experiment may finally resolve the intentionality/causality question. In this study, the demonstration of an identical
pattern of results to the original Libet Clock experiment could resolve this issue. As such, I believe the removal of intention from the cause-effect sequence should be the next step in the investigation of the Temporal Binding phenomenon.