Presentation of neuroscientific tools
| Tool | Form of analysis | Description | Strengths | Limitations | Most appropriate for research | Studies that used the tool |
|---|---|---|---|---|---|---|
| Anatomical imaging* | Brain images | MRI scanner measures static differences in brain anatomy | Good spatial resolution Identify differences in the volume of basic tissue types in the brain Assess structural connectivity of the brain | The significance of differences in white matter volume is not well understood Reliable individual difference studies require large N (>50) | Tests hypotheses about individual differences between brain anatomy/volume/connectivity/microstructure and cognition/behavior | |
| Electroencephalography (EEG)* | Brain electrical activity | Electrodes placed on the scalp to measure electrical changes that result from neural activity | Longest established method Strongest temporal resolution (with MEG) Less expensive than fMRI or MEG Portable – not constrained to scanner Allows realistic interaction between subjects | Sensitive to other sources of electrical current (e.g. muscular activity) Detects signals that are not wholly spatially independent, creating an inverse problem | Requires face-to-face interaction between subjects Tests hypotheses about the timing of cognitive processes Tests hypotheses related to known and reliable ERP signatures (e.g. N400, mismatch negativity) Tests hypotheses relating to high-frequency neuronal oscillations (e.g. alpha and gamma) | Balthazard et al. (2012) Deitz et al. (2016) Geske and Bellur (2008) Hannah et al. (2013) Daugherty, Hoffman and Kennedy (2016) Telpaz et al. (2015) Pozharliev et al. (2015) Gountas et al. (2019) |
| Eye-tracking | Eye movement | Assistive technology allows one to assess and research an individual's eye movements revealing where to visual attention is directed | Identifies in which areas the person fixes their attention, for how long and in what order they follow their visual exploration It can be done either in closed or open environments, dynamically or statically, for activities carried out in a natural or controlled environment, allowing various applications | The equipment and software, as most commercial products still have a high average price Although this technology is becoming cheaper and even though there are free solutions for conducting and analyzing experiments, the technical reliability of low-cost solutions can be challenging | It can be used in product and service interaction activities, sports, occupational or leisure activities, contributing to knowledge about eye movement and its relationship with cognitive processes | Gerpott et al. (2018) Meißner, Oppewal and Huber (2020) Maran et al. (2019) Federico and Brandimonte (2019) Federico et al. (2021) Ceravolo et al. (2019) Venkatraman et al. (2012) Meißner et al. (2020) |
| Facial action coding system (FACS) | Facial expressions | It is a scientific measurement system of facial actions/movements in human beings | Researchers can manually label almost any anatomically possible facial expression | Labeling expressions require trained experts | Used to analyze the emotions displayed on the face, differentiating them through the movement of the facial muscles | |
| Facial electromyography | Muscles electrical impulses | It is a tool that measures muscle activity by detecting and amplifying the small electrical impulses generated by muscle fibers when they contract | It is the most reliable tool to assess reactions with emotional valence by placing bipolar electrodes on two facial muscles It is not language-dependent and does not require cognitive effort or memory It can measure the activities of facial muscles to weakly evocative emotional stimuli It is less intrusive than other physiological measures It is often the only helpful approach when movement is not visible | Although commonly used as an index of emotional responses, facial muscle activity is also influenced by the social context in which it is measured | Used to verify emotional valence (positive or negative), measure social cognition (empathic states) and situational awareness It has been used to distinguish and track positive and negative emotional reactions to a stimulus as they occur | Minas et al. (2014) Zellars et al. (2008) |
| Functional magnetic resonance imaging (fMRI)* | Brain metabolical activities and images | Indirectly measures neural activity via changes in oxygenation level in blood Depends on the function of endogenous biological mechanism by which neuronal activity leads to changes in blood flow (“neurovascular coupling”) | Captures entire brain Offering rich spatial information, provides a good foundation for inferences about function | Limited to tasks that can be performed in a scanner Cannot easily distinguish top-down from bottom-up signals Measurements are not strictly quantitative (units are not biologically meaningful) | Uses localization of function, forward inference or reverse inference (see discussion) Assesses functional connectivity of regions during tasks or rest Assesses changes in brain function before/after intervention Assesses neural basis of individual differences | Molenberghs et al. (2017) Boyatzis et al. (2012) Laureiro-Martínez et al. (2014) Plassmann et al. (2008) Berns and Moore (2012) |
| Functional near-infrared spectroscopy (fNIRS)* | Brain metabolical activities | Indirectly measures neural activity by detecting changes in near-infrared light, which reflect changes in the amount of (de)oxygenated hemoglobin in the blood Depends on neurovascular coupling, similar to fMRI | Has better temporal resolution and is cheaper than fMRI No cost after initial purchase (e.g. maintenance) Portable Participant does not need to remain stationary, as with other imaging techniques Similar to EEG, allows realistic interaction between subjects | Lower spatial resolution and lower signal-to-noise ratio, compared to fMRI Can only detect metabolic activity on the cortical surface (approximately only 4 cm underneath the skull) | Tests hypotheses for tasks that are not optimally suited for fMRI paradigms (e.g. those requiring movement or face-to-face social interaction) Involves longitudinal studies, given the relatively low cost | Lee and Yun (2017) Meyerding and Mehlhose (2020) |
| Galvanic skin response (GSR) | Glands electric activity | It measures the electrical activity of glands that produce sweat in the palms of the hands and fingertips, which are more sensitive to emotions and thoughts | The more stimulated the central nervous system, the more sweat the glands will produce and the less resistance will be measured on the electrodes, thus increasing the amplitude of the circuit's output signal Although this response is not always visible (sweat), there is a change in skin resistance because of psychological changes such as increased arousal and anxiety | Individuals may experience a gradual loss of motor faculties | It is widely used in learning relaxation in general and to help identify situations that cause stress and anxiety | Christopoulos, Uy and Yap (2019) Kouchaki and Wareham (2015) Reimann et al. (2012) |
| Magnetoencephalography (MEG)* | Records electrical activity in the brain | Magnetometers near the scalp measure magnetic fields generated by neural activity | More reliable and accurate than EEG because magnetic permeability of head is more uniform than electrical conductivity, which simplifies inverse solution calculations | More expensive than EEG Not portable Very sensitive to external noise Signal falls off with a cube of distance – deeper brain structures very hard to detect Most sensitive to activity in regions that are perpendicular to the skull surface | Tests hypotheses about the timing of cognitive processes, neuronal oscillations and connectivity between regions Combined with EEG, it allows more signals to be detected and improved solutions to the inverse problem | |
| Positron emission tomography (PET)* | Records metabolic activity in the brain | A radioactive tracer is inserted into the bloodstream | O15 tracer measures blood flow in absolute terms Can measure other biological markers (e.g. glucose isotope provides an absolute measure of metabolic activity) | A small number of measurements per subject Low spatial and temporal resolution compared to fMRI Ethical issues arise from the fact that this is an invasive technique involving intravenous administration of radioactive isotopes Limit to a number of scanning sessions per individual to reduce radiation exposure Requires nearby cyclotron to produce isotopes Accurate anatomical localization requires a separate MRI scan | As for fMRI has limited application to functional connectivity Superior to fMRI for assessing the neural basis of individual differences (absolute measure not confounded by irrelevant factors) | |
| Steady state topography | Records electrical activity in the brain | It is a methodology for observing and measuring human brain activity | High temporal resolution: SST methodology is able to continuously track rapid changes in brain activity over a long period of time The SST methodology is able to tolerate high levels of noise or interference because of head movements, muscle tension, blinking and eye movements Suitable for cognitive studies where eye, head and body movements occur naturally | It needs to be used in conjunction with other tools | Used with audiovisual materials and/or during a psychological task to record the brain's electrical activity | |
| Transcranial direct current stimulation (tDCS)* | Records electrical activity in the brain | Coil is used to suppress (occasionally to enhance) neural activity using an electrical current Single-pulse (very brief effect) and repetitive pulse methods (*15 min effect) can be used | Allows for within-participant comparisons that sidestep endogeneity concerns Good temporal specificity is possible with a single pulse Portable – not confined to the scanner With specialized equipment, virtual lesion location can be pinpointed to regions were shown to be activated by fMRI | Generally, it can only affect the dorsal, lateral and occipital cortical surfaces (but see deep brain TMS) Directly affects only isolated regions, but the impact on networks/other regions is not fully known Impact of machine noise and skeletal muscle enervation on task performance requires careful control | Tests hypotheses related to the necessity a particular brain region might have for cognition and behavior; tests and resolves concerns about reverse inference | |
| Transcranial magnetic stimulation (TMS)* | Records electrical activity in the brain | Similar to TMS but uses a constant current applied through patch electrodes | Enable brain to causal cognition with more confidence because of direct stimulation of neural activity Portable Well tolerated by participants It can both increase and decrease neuronal excitability Effects last longer than TMS The technique is developing rapidly with numerous technical innovations | Anatomical location of effects is hard to assess Less spatial and temporal control than TMS Recent meta-analysis suggests no statistically reliable effects, although ongoing advances may overcome shortcomings | Tests hypotheses related to the necessity cortical areas might have for cognition, behavior and learning | Camus et al. (2009) |
| Tool | Form of analysis | Description | Strengths | Limitations | Most appropriate for research | Studies that used the tool |
|---|---|---|---|---|---|---|
| Anatomical imaging* | Brain images | MRI scanner measures static differences in brain anatomy | Good spatial resolution | The significance of differences in white matter volume is not well understood | Tests hypotheses about individual differences between brain anatomy/volume/connectivity/microstructure and cognition/behavior | |
| Electroencephalography (EEG)* | Brain electrical activity | Electrodes placed on the scalp to measure electrical changes that result from neural activity | Longest established method | Sensitive to other sources of electrical current (e.g. muscular activity) | Requires face-to-face interaction between subjects | |
| Eye-tracking | Eye movement | Assistive technology allows one to assess and research an individual's eye movements revealing where to visual attention is directed | Identifies in which areas the person fixes their attention, for how long and in what order they follow their visual exploration | The equipment and software, as most commercial products still have a high average price | It can be used in product and service interaction activities, sports, occupational or leisure activities, contributing to knowledge about eye movement and its relationship with cognitive processes | |
| Facial action coding system (FACS) | Facial expressions | It is a scientific measurement system of facial actions/movements in human beings | Researchers can manually label almost any anatomically possible facial expression | Labeling expressions require trained experts | Used to analyze the emotions displayed on the face, differentiating them through the movement of the facial muscles | |
| Facial electromyography | Muscles electrical impulses | It is a tool that measures muscle activity by detecting and amplifying the small electrical impulses generated by muscle fibers when they contract | It is the most reliable tool to assess reactions with emotional valence by placing bipolar electrodes on two facial muscles | Although commonly used as an index of emotional responses, facial muscle activity is also influenced by the social context in which it is measured | Used to verify emotional valence (positive or negative), measure social cognition (empathic states) and situational awareness | |
| Functional magnetic resonance imaging (fMRI)* | Brain metabolical activities and images | Indirectly measures neural activity via changes in oxygenation level in blood | Captures entire brain | Limited to tasks that can be performed in a scanner | Uses localization of function, forward inference or reverse inference (see discussion) | |
| Functional near-infrared spectroscopy (fNIRS)* | Brain metabolical activities | Indirectly measures neural activity by detecting changes in near-infrared light, which reflect changes in the amount of (de)oxygenated hemoglobin in the blood | Has better temporal resolution and is cheaper than fMRI | Lower spatial resolution and lower signal-to-noise ratio, compared to fMRI | Tests hypotheses for tasks that are not optimally suited for fMRI paradigms (e.g. those requiring movement or face-to-face social interaction) | Lee and Yun (2017) |
| Galvanic skin response (GSR) | Glands electric activity | It measures the electrical activity of glands that produce sweat in the palms of the hands and fingertips, which are more sensitive to emotions and thoughts | The more stimulated the central nervous system, the more sweat the glands will produce and the less resistance will be measured on the electrodes, thus increasing the amplitude of the circuit's output signal | Individuals may experience a gradual loss of motor faculties | It is widely used in learning relaxation in general and to help identify situations that cause stress and anxiety | |
| Magnetoencephalography | Records electrical activity in the brain | Magnetometers near the scalp measure magnetic fields generated by neural activity | More reliable and accurate than EEG because magnetic permeability of head is more uniform than electrical conductivity, which simplifies inverse solution calculations | More expensive than EEG | Tests hypotheses about the timing of cognitive processes, neuronal oscillations and connectivity between regions | |
| Positron emission tomography (PET)* | Records metabolic activity in the brain | A radioactive tracer is inserted into the bloodstream | O15 tracer measures blood flow in absolute terms | A small number of measurements per subject | As for fMRI has limited application to functional connectivity | |
| Steady state topography | Records electrical activity in the brain | It is a methodology for observing and measuring human brain activity | High temporal resolution: SST methodology is able to continuously track rapid changes in brain activity over a long period of time | It needs to be used in conjunction with other tools | Used with audiovisual materials and/or during a psychological task to record the brain's electrical activity | |
| Transcranial direct current stimulation (tDCS)* | Records electrical activity in the brain | Coil is used to suppress (occasionally to enhance) neural activity using an electrical current | Allows for within-participant comparisons that sidestep endogeneity concerns | Generally, it can only affect the dorsal, lateral and occipital cortical surfaces (but see deep brain TMS) | Tests hypotheses related to the necessity a particular brain region might have for cognition and behavior; tests and resolves concerns about reverse inference | |
| Transcranial magnetic stimulation (TMS)* | Records electrical activity in the brain | Similar to TMS but uses a constant current applied through patch electrodes | Enable brain to causal cognition with more confidence because of direct stimulation of neural activity | Anatomical location of effects is hard to assess | Tests hypotheses related to the necessity cortical areas might have for cognition, behavior and learning |
Notes:
Prepared from different sources in this work; the items marked *are from the work by Jack et al. (2019, pp. 425–427)
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