## 2 Materials and Methods
### Cognitive Performance
#### 2.5.1 Limited or No Negative Impacts on Cognitive Abilities  
[PERSON] et al. explored the impact of short-term exposure to GSM and UMTS cell phone base station signals on the cognitive performance of 200 Malaysian subjects. The study found that there were no significant negative impacts on the cognitive performance or heart rate for both normal and sensitive subjects, indicating the absence of association and link between EMF exposure and potential negative health consequences [23]. However, the study only examined short-term exposure and did not examine the impact on specific cognitive functions or long-term exposure. Therefore, the results are limited and cannot be generalized to other cognitive functions or long-term exposure. [PERSON] et al. conducted another separate experiment to investigate the impact of pulse-modulated and continuous-wave RF-EMF on cognitive performance and brain activity in 24 healthy young men [24]. The study found that exposure to this type of RF-EMF signal for 30 min at a precise absorption rate of 1 \(W\)/kg reduced reaction time and improved reliability in a working-memory test. The authors deduced that pulse-modulated RF-EMF has a non-thermal biological effect on cognitive performance and specific brain activity, but the underlying physiological mechanisms are still unclear. The study also emphasized the necessity for a valid tool to appraise the specific impacts of RF-EMF exposure on cognition. [PERSON] et al. examined the consequence of daily MP (mobile phone) usage on cognitive performance in a sample of 55 people, half of whom kept their MPs on and the other half who left them off. The 45-day study included daily exposure to a 900 MHz wave pulsed at a frequency of 217 Hz for two hours. During the study, the participants were subjected to a neuropsychological test consisting of 22 tasks that observed four neurocognitive sub-categories. Despite the absence of a statistically meaningful interaction between exposure  
Figure 3: (**a**) Exposure chamber, (**b**) RF-EMF exposure on a male subject in a sitting position (top view) [22]. and the allocated time frame, the findings indicated that the MP exposure had no impact on cognitive performance following a 13-h rest period [25]. The study concluded that daily MP use does not have a medium-term effect on cognitive function. However, the study's limitations prevented the assertion of any effects from longer exposures. [PERSON] et al. investigated the impact of electromagnetic waves created by 3G and 4G (LTE) cellular phones on cognitive skills, specifically reaction time and short-term memory, in a sample of 85 medical students aged 18-22 years. The findings indicated that exposure to electromagnetic waves resulted in a slower response time among the students, whereas no significant effect was observed on short-term memory [26]. The study further recommended that the frequency of electromagnetic waves might be responsible for the slower response time to stimuli. [PERSON] et al. [27] recently discovered short-term RF exposure from current-generation cellphones. In a double-blind and randomly balanced study, the authors looked into the impact of 3G and 4G radio frequency EMF exposure on the usual cognitive abilities indicated in the Stroop test analysis. The study included 60 young adults who were in decent health (34 for 3G UMTS and 26 for 4G LTE). The Stroop test, however, demonstrated that these frequency signals did not significantly influence the executive function measures, speed of processing, or selective attention. Thus, UMTS and LTE exposure had no discernible influence on the attentional processing metrics found in the Stroop test. [PERSON] et al. investigated the potential effects of electromagnetic fields (EMFs) emitted by mobile phones on cognitive functions. Their research focused on assessing the impact of GSM 900 and WCDMA signals on attention and working memory in a group of 30 young male subjects.