Revisiting variable foreperiod effects evaluating the repetition priming account
Tianfang Han & Robert W. Proctor
Abstract
A warning signal preceding an imperative stimulus by a certain foreperiod can accelerate responses (foreperiod effect)
When foreperiod is varied within a block, the foreperiod effect on reaction time (RT) is modulated by both the current and the prior foreperiod
The multiple-trace theory of Los et al. (Frontiers in Psychology, 5, Article 1058, 2014) attributes the slope of the foreperiod-RT function to the foreperiod distribution
with a non-aging foreperiod distribution, the variableforeperiod paradigm yields unequal sequential-effect sizes at the different foreperiods, consistent with the multiple-trace theory but contrary to Capizzi et al.’s repetition-priming account
The foreperiod-RT functions are similar to those of the fixedforeperiod paradigm, which is not predicted by the multiple trace theory
Experiment 1
Both the foreperiods and foreperiod distribution were the same, but a choice-reaction task
Responses were faster when the current foreperiod was 400 ms compared to 1,400 ms
was also a main effect of Foreperiod Sequence,
Responses were faster when the current foreperiod was the same as the previous one compared to when they were different.
the interaction of Current Foreperiod × Foreperiod Sequence indicated that the SFP effect was larger at the short foreperiod than at the long foreperiod
This result is inconsistent with the repetition priming account of Capizzi et al., according to which the SFP effects should be of similar sizes at short and long foreperiods
The larger SFP effect at short than long foreperiods is consistent with Los et al.’s (2014) multiple trace theory
This is because it assumes that a long previous foreperiod produces inhibition to the critical moment of the short foreperiod but a short previous foreperiod does not affect the preparation at the critical moment of the long foreperiod
symmetric sequential effects are more likely to be found in choicereaction tasks compared to a simple reaction scenario.
the larger proportion of shorter foreperiod trials could be the basis of that foreperiod’s advantage in terms of response speed by having more previous memory traces contributing to the activation at the shorter foreperiod’s critical moment
Alternatively, the increasing foreperiod-RT function in Experiment 1 shared the same direction as in a fixedforeperiod paradigm
without the effect from the additional processes in a variable-foreperiod paradigm, the foreperiod-RT relation in the two foreperiod paradigms will be in the same direction
Experiment 2
two very short foreperiods (50 ms and 200 ms) were used
This prediction means that the shorter preceding foreperiod should produce faster responses regardless of the length of the current foreperiod
Based on the current assumptions of MTP, the preparation at any foreperiod is determined by the activationinhibition states (strengths of activation and inhibition) stored in each [memory trace], the strength of each [memory trace] ([memory trace](memory trace], the strength of each [memory trace] ([memory trace.md) is more dispersed and weaker as the foreperiod gets longer), and the total number of previous memory traces with each foreperiod
Participants were more likely to make errors when encountering foreperiod repetition compared to alternation
main effect of Current Foreperiod was not significant
The interaction between Foreperiod Sequence and Current Foreperiod was not significant
First, the main effect of Current Foreperiod was found, indicating a decreasing foreperiod-RT function in the short-foreperiod scenario
This direction is consistent with the prediction based on the fixed-foreperiod effect but this foreperiod-RT function, especially its opposite direction from that observed in Experiment 1, cannot be predicted from the current assumptions of the MTP
A small interaction was found between Current Foreperiod and Foreperiod Sequence
It is worth noting that participants were more likely to make errors when the current foreperiod matched the previous one compared to when it did not
Experiment 3
The main effect of Current Foreperiod was not significant
neither was the interaction between Current Foreperiod and Foreperiod Sequence
With regard to the variable-foreperiod effect, although a significant main effect was not detected (p = .085), the numerical difference in RT at the two foreperiods pointed in the same direction as the significant fixedforeperiod effect
Discussion
Los et al. (2017) used a visual warning signal and a visual imperative stimulus and found that blocks with the same foreperiod distribution (exponential or antiexponential) induced a short-term carryover effect on the foreperiod-RT function in subsequent blocks with a uniform distribution
Crowe and Kent (2019) used an auditory pair of stimuli and found a similar but more limited carryover effect (lasting for only one block)
imply that having the fixed-foreperiod blocks performed immediately after the variable-foreperiod blocks could have made it more difficult to measure the fixed-foreperiod effect precisely, which could be a potential limitation of the current design
The key step of reconnecting the two foreperiod paradigms was taken by Los et al. (2014), in which a simplified version of the MTP without the activation-inhibition ratio was used to account for the fixedforeperiod effect
A lower maximum and greater temporal dispersion as the imperative moment is moved further from the warning signal were added to predict a shorter RT at the short foreperiod
by using a non-aging foreperiod distribution, the variableforeperiod effect would get back to its baseline, which is the foreperiod-RT function in a fixed-foreperiod paradigm
Conclusion
The results of this study suggest that the SFP effect reflects a benefit of repetition, which can be attributed to the memory of prior trials
SFP effect was larger at the shorter foreperiod, which is consistent with MTP
On the other hand, we showed that in a variable foreperiod paradigm, when the conditional probability of the imperative stimulus appearing at the next foreperiod stays constant over time, the foreperiodRT function follows the foreperiod-RT relation in a fixed foreperiod paradigm.
This consistency between different foreperiod paradigms is not predicted by the MTP, which attributes the foreperiod-RT function to the proportions of foreperiods
