We live in a complex and dynamic world where sometimes our action yields the intended (desired) outcomes and sometimes the unintended outcomes, but does our subjective time changes as a function of outcome being intended or unintended. To find the answer, read the recent article by Mukesh Makwana and Prof. Narayanan Srinivasan, published in Scientific Reports.
In a series of five experiments involving temporal bisection task (Exp1-4) and magnitude estimation task (Exp5), they investigated whether participants perceive the duration of intended outcome differently compared to unintended outcome, and if yes then what are its underlying mechanisms.
They reasoned that when a participant intends an outcome, its representation gets activated and this prior self-activated representation would lead to earlier awareness of the intended outcome compared to unintended outcome extending the temporal experience. Recently, pre-activation account has been used to explain temporal expansion (Press et al., 2014).
To manipulate intentional nature of the outcome they used a simple color choice question. In each trial, amongst the choice of two colors, they asked participants to indicate what color circle they want to see, by pressing the allocated key for that color. After 250ms (Exp1) of the intentional key press, they were randomly presented with circle of either intended color (50% times) or unintended color (50% times) whose duration was randomly manipulated amongst nine levels (300ms to 700ms in steps of 50ms). This was done to reduce or eliminate the sensory-motor prediction between the key press and the color of the outcome circle, so that the effect of intention on the perceived duration of the outcome is not confounded with probability-based prediction. Irrespective of the intentional nature of the outcome, participants were supposed to report whether they perceived the duration of the outcome as closer to short (300ms) or long (700ms) anchor duration that they learnt in training phase before the main experiment. Each individual data was sorted into two conditions i.e. when they get the intended outcome (i.e. Intended condition) and when they did not get the intended outcome ( i.e. unintended condition). Psychometric (Weibull) functions were fitted for this two conditions and bisection points were calculated. Bisection point or point of subjective equality is the measure of shift in temporal perception, where lower values of bisection point in a condition indicate temporal expansion relative to condition with higher bisection point. Results of Exp1 showed that participants perceived the duration of intended outcome as longer compared to unintended outcome.
They also studied whether increase in delay between the intentional action and its outcome affects the intention induced temporal expansion observed in Exp1. So further two experiments were performed with increased delay between action and outcome i.e. 500ms in Exp2 and 1000ms in Exp3. Rest stimuli, apparatus and procedure were identical to Exp1 except that in Exp2 instead red and green, yellow and blue color circles were used. Results showed that the intention induced temporal expansion was observed till 500ms delay but as the delay increased to 1000ms the temporal expansion effect vanished, suggesting that the self-activated representation fades away around 1000ms of the intentional action.
To establish that for the above-observed temporal expansion effect, intentional activation of the representation is necessary and not just priming or instruction-based action is not sufficient Exp4 was performed. In Exp4, instead of intending and selecting what color circle they wanted to see, in each trial participants were shown color word i.e. RED or GREEN on the screen and they just pressed the corresponding key. Rest procedure, stimuli and analysis was similar to Exp1. Results showed no difference in duration perception between word congruent condition and word incongruent condition, suggesting the importance of intention in the above effect.
Lastly, Exp5 was performed using magnitude estimation paradigm to investigate whether intention affects the time perception by increasing the pacemaker speed or affecting the switch or gating component of the “internal clock model”. The internal clock model is the most influential classical model used to explain human timing behaviour. If any factor influences the pacemaker speed then as the magnitude of the actual duration increases the difference between two conditions should also increase given a typical “slope effect”. On the other hand, if the switch or gating component is affected then no slope effect is observed. Results showed no slope effect, indicating that intention might influence the switch or gating mechanism.
In conclusion, a series of experiments in this study provides convincing evidence that intention affects temporal perception and participants perceives the intended outcome to be longer in duration compared to unintended outcome. Moreover, this intention induced temporal expansion effect depends on the temporal contiguity between the action and the outcome and it vanishes at 1000ms action-outcome delay. Furthermore, in terms of internal clock, this effect is most probably not due to increase in pacemaker speed, rather opening or closing of the switch seems more probable mechanism. As humans are intentional agents and intentions forms a critical part of daily life, more studies investigating the effects of intention on perception in general should be pursued.
Reference:
Source article: Makwana, M., & Srinivasan, N. (2017). Intended outcome expands in time. Scientific Reports, 7(6305) doi: 10.1038/s41598-017-05803-1
—Mukesh Makwana (mukesh@cbcs.ac.in),
Doctoral student,
Centre of Behavioural and Cognitive Sciences (CBCS), India.
