Blocked vs. Interleaved: How range contexts modulate time perception and its EEG signatures
Cemre Baykan, Xiuna Zhu, Artyom Zinchenko, Zhuanghua Shi
General and Experimental Psychology, LMU Munich
Background
Accurate time perception is a crucial element in a wide range of cognitive tasks, including decision-making, memory, and motor control. One commonly observed phenomenon is that when given a range of time intervals to consider, people's estimates often cluster around the midpoint of those intervals. Previous studies have suggested that the range of these intervals can also influence our judgments, but the neural mechanisms behind this "range effect" are not yet understood. We used both behavioral tests and electroencephalographic (EEG) measures to understand how the range of sample time intervals affects the accuracy of people's subsequent time estimates. Study participants were exposed to two different setups: In the "blocked-range" (BR) session, short and long intervals were presented in separate blocks, while in the "interleaved-range" (IR) session, intervals of various lengths were presented randomly. Our findings indicated that the BR context led to more accurate time estimates compared to the IR context. In terms of EEG data, the BR context resulted in quicker buildup of Contingent Negative Variation (CNV), which also reached higher amplitude levels and dissolved more rapidly. We also observed an enhanced amplitude in the offset P2 component of the EEG signal. Overall, our results suggest that the variability in time intervals, as defined by their range, influences the neural processes that underlie time estimation.
Experimental design
Each trial started with a randomly timed fixation, ranging between 1.3 and 2.3 s. This was immediately followed by a 0.7 s appearance of an exclamation mark, signaling the imminent tone and the upcoming “encoding phase”. The tone played for a specific duration (elaborated further in the next paragraph) while the exclamation mark remained on the screen. It was then replaced by a question mark, prompting for the upcoming “reproduction phase”. After 1.5 s, the reproduction phase started with another tone played, while the question mark remained visible. Participants were tasked with stopping this tone - by pressing the spacebar - once it matched the initial tone’s duration.
The experiment comprised two sessions: the blocked range (BR) and the interleaved range (IR) contexts. In the BR session, participants encountered subseconds (0.4, 0.57, and 0.8 s) or supra-second intervals (1.2, 1.7, and 2.4 s) in separate blocks. Crucially, to ensure that interval ranges were non-overlapping, we introduced a 0.4 s chasm between the ranges. The order of the types of blocks was counterbalanced among participants. Meanwhile, in the IR session, participants were exposed to the full range of target intervals - extending from sub-seconds to supra-seconds (0.4, 0.57, 0.8, 1.2, 1.7, and 2.4 s). Participants always started with the BR session, ensuring they never encountered the full range before completing the BR. They had at least a 10-min break between sessions.
Data and Analysis Code Folder Structure
- /derivates:
"Behavioral_analysis.Rmd": behavioral data analyses,
"EEG_analysis.Rmd": ERP analyses.
- /data:
"allAverageDat_beh.csv": behavioral data
"allAverageDat.csv": CNV data
"allAverageDat_short.csv": CNV data for plotting
"allAverageDat_resp.csv": response-onset locked data for LPCt analysis
"allAverageDat_p2.csv": target-offset locked data for P2 analysis
"cnv_width_per.csv": CNV dissolving latency data during encoding
"cnv_width_rep.csv": CNV dissolving latency data during reproduction
- /figures: stored figures used in the paper
