Taking advantages of the temporal resolution of event-related potentials (ERPs), we investigated the voltage deflections that reflect the attribution of meaning to activity pictures. ERPs are one of the most informative and dynamic methods of monitoring the information flow in the human brain (Duncan et al., 2009). This method can reflect the reception and processing of sensory information as well as higher level processes such as attention, memory, comprehension, and other types of cognitive activity.
To our knowledge, this was the first study that investigated meaning in activities using ERPs. Our aim was to discover if the attribution of meaning in meaningful activity picture stimuli elicited ERP responses other than non-meaningful picture stimuli. The P1-N1-P2 complex could be observed in the grand averages which is related to primary cognitive and visual processing of the stimuli (Song et al., 2005). The visually observable negative deflections in the grand averages showed the potential presence of the N200 and N400 component. However, the paired t-test showed no effect between the mean amplitudes of the meaningful and non-meaningful condition in five time windows related to P1, N1, P2, N200, and N400. The onset latency of the deflections in these time windows showed also no significant difference between the two conditions.
Our results showed no effect of condition and no interaction effect between condition and brain region so the amplitudes in the time windows of N200 and N400 could not reflect the attribution of meaning in the general sample of the participants. Considering these non-significant findings in the general sample, we looked at the ERPs on an individual level. Since the attribution of meaning is very individual, some cases can provide more visual information about the difference between the ERPs of the two conditions. The single-subject visual inspection showed small variations in the differentiations, but varied in time and direction. A major factor in this variability across subjects could be the unique idiosyncratic folding pattern of the cortex in each individual (Luck, 2014). This way of interpreting makes it thus very subjective and less reliable since the variation in the ERPs can be attributed to the signal-to-noise ratio (Blankertz et al., 2011). The grand averages should be therefore inspected because they are more robust and more reliable.
As the results showed no general effect of condition in the N200 and N400 time window, the hypothesis that a meaningful activity stimulus is reflected in one’s N200 and/or N400 component could not be confirmed.
Due to the innovative character of this study, the new paradigm should be discussed. This paradigm differs from other standardized visual paradigms in that the stimuli are not predetermined by the researcher what was meaningful and not meaningful. A closer look into the individual answers revealed that the participants rate the stimuli differently from a behavioural point of view. Some participants scored a very high number of meaningful activities, where others scored equally or lower compared to the NMF activities. The concept of meaningful activity has a subjective nature as a result of which participants had a different interpretation of the assignment. Also, notation can be made that some individuals have a stronger mental imagery than others (Keogh and Pearson, 2014). They have the ability to form more vivid images of the activities seen on the pictures which can influence the scores on the VAS scale. Perhaps the cut-off score of 5 could be revised to a higher cut-off, for example 7 or 8, to be more confident that we captured the meaningful stimuli from the participants. Since the assignment of trials to the two conditions is based on participant’s responses, it was quite likely that the data was unbalanced. We decided to equalize the trials in each condition to reduce signal to noise but could result in the loss of valuable data.
The paradigm consisted of similar activities mentioned by different participants but with minor nuances such as the context, or amount of persons. This is not surprising knowing that the types of activity people like to perform is gender specific (Sharp et al., 2007). Since we included only women, the type of activities they attached meaning to were more social activities (Cruyt et al., 2021). Perhaps due to these small nuances in those activities, this led to insignificant results in the N200 and/or N400 effect. It would be appropriate to enrich the paradigm with more versatile activities, by including for example also men. On the other side, including right-handed females in the study contributed to the homogeneity since research found that functions in the brain can vary among gender (Zaidi, 2010; Xin et al., 2019), just as the brains of left-handers differ from right-handers (Guadalupe et al., 2014).
No standardized pictures from databases were used in this paradigm since the pictures were too individualised. The pictures were retrieved from the internet bearing the risk that they could not be controlled for specific visual features that can introduce unwanted variability in the data (e.g., colors, resolution, faces, or spatial frequency). It was also a challenge to find pictures that completely complied to the mental image of the participants. The question can be asked if the perception of meaning can be elicited through a picture that does not contain participant’s personal information (such as own house, own material, etc.). As a consequence the pictures we used might be too less self-relevant or participants felt them as too distal. Therefore our non-significant results might reflect that the activity pictures we applied are not or insufficiently triggering a meaningful attribution and inducing too less arousal or activation to induce fluctuations in brain activation in participants. Further research might make the pictures more self-relevant by explicitly referring to participants’ self-concept or personal prior activity-related experiences (e.g. in the wording of the instructions; using personal second-person wording (‘imagine You are doing the displayed activity’) as opposed to rather removed third-person wording). Self-referencing has been described in the literature as a cognitive process whereby individuals associate self-relevant incoming information (e.g. a picture) with information previously stored in memory (e.g. one’s self-concept; prior activities) in order to give the new information meaning or to trigger prior stored cognitive evaluations such as meaningfulness (Markus, 1980). Prior consumer psychological and advertising research, in which images are often used, suggests that self-referencing has a considerable impact on recall of information (Sujan et al., 1993), as well as on product evaluations (Meyers-Levy and Maheswaran, 1991).
Two alternative pathways might overcome this challenge as well. Firstly, the picture should be taken in the real context where the activity is performed and with the right persons, recognizable material etc. This would also eliminate the cognitive process of secondary representation. But therein lies the risk that we would measure recognition instead of meaning, which would also give a N200 and N400 effect but would be based on wrong assumptions. Otherwise, to eliminate the cognitive processes related to recognition, the researcher can gather picture stimuli of potential meaningful activities from databases without asking the participants beforehand about their meaningful activities. In that case, no expectations or recognition will appear during the paradigm. Thirdly and for further research, it is recommended to determine in a pilot study with experts and lay people in advance of the data-collection the extent towards the list of selected activity pictures are reflecting meaningfulness or not. As a kind of manipulation check this could also be verified by asking this for each picture at the end of the experiment at the participants themselves.
The attribution of meaning to personal experiences rest on a specialized cognitive system that takes perhaps more time than we defined (Bering, 2003). It has been suggested that there needs to be time for reflection, where meaning can be experienced (Reed et al., 2010). Maybe, we should look to the attribution of meaning as a longer cognitive process and not merely as a quick physiological response that can appear in milliseconds after showing a picture stimulus of a meaningful activity. The participants should first ‘translate’ or ‘process’ the activity picture to their own perception and must therefore appeal to the semantic memory, the individuals’ store of knowledge about the world and daily activities (Binder and Desai, 2011). It is the conceptualization from past actual experience throughout an activity. More specific, the episodic memory might be used which has more particular knowledge of specific events.
Also previous research corroborates the idea that the attribution of meaning is as a prolonged cognitive process and can be considered as an outcome of one’s cognitive information processing. Indeed, research has proven that the correlation between latencies of ERP components and cognitive abilities have been inconsistent and that there is a moderately negative relationship between latencies of ERP components associated with higher-order cognitive processing and cognitive abilities (Euler and Schubert, 2021).
Moreover, the ERP components are sensitive to psychological variables (e.g. one’s mood, personality) but not generally reducible to specific psychological constructs (Kutas and Federmeier, 2011). Bering (2003) stated that affective judgment (the self-evaluation of the activity as meaningful or not) is necessary to be perceived as meaningful but is far from sufficient to capture meaning. Concluding on these empirical evidence, ERP is perchance not the right technique to use to answer our research question.
Further research
Research stated that factors that promote the attribution of meaning in life events and experiences cannot easily be systematically controlled and manipulated (Bering, 2003). These experiences are hard to simulate in the laboratory or to capture the emotional and cognitive states that accompany activities in the real world. As for meaning in activities, this theory can also apply. Reasonably, the person needs to perform the activity while measuring with brain techniques to capture meaning. This method allows the participant to perform the activity in the own environment since this aspect is also important for the attribution of meaning to an activity (Hasselkus, 2011). A person should experience his meaningful activity, with sight, hearing and smell as important factors for the perception of meaning in the activity in the environment. Since little is known about the neural correlates of meaning in activities of daily living, several methods can be used to find an answer on which regions in the brain are activated when people attribute meaning to activities.
In the last decade, a more portable EEG set up has potential to identify neurological electrical activity while people are engaged in daily activities (Bankman and Morcovescu, 2002; Gutman and Schindler, 2007). As a starting point, the theory of flow, where alpha wave activity is considered as a key physiological remark, can give directions in the search for meaning in the brain since these two are related (Cruyt et al., 2023). Flow is a psychological state of optimal experience of an activity (Csikszentmihalyi, 2014). The person enjoys the activity, is fully engaged, intensely focused and absorbed in the activity. Flow can occur in every activity of daily life and is associated with positive outcomes such as well-being and personal fulfilment. However, good measurements of an EEG still requires the controlling of different variables. Therefore, feasibility seems to be less good for our research design.
Another relatively new brain registration technique, the functional near infrared spectroscopy (fNIRS), can be used in an unconstrained and more realistic environment because it comes with a wireless device. It is non-invasive and uses infrared light to estimate cortical hemodynamic activity in the brain which occurs in response to neural activation (Sato et al., 2013). The main advantages are the portability, less expensive, and has a higher temporal resolution (Niu et al., 2013). The validity of the signals can be compared with the Blood Oxygenation Level Dependent (BOLD) signals as measured by fMRI and have the additional advantage of displaying more directly interpretable physiological signals (Wright and Wise, 2018; Balardin et al., 2017).