Ghost sensations reveal a split between body image and reality

Have you ever sat quietly in a chair, attempting to relax, only to be interrupted by a sudden itch on your foot or a tingling in your hand? A new study published in the Quarterly Journal of Experimental Psychology investigates these “ghost” bodily experiences. The findings suggest that our general mental map of our body differs from how we perceive sensations in the immediate moment.

The human nervous system is rarely silent. Even in the absence of external stimuli, such as a fly landing on the skin or a change in wind direction, we often perceive activity within our limbs. Researchers refer to these phenomena as spontaneous sensations. They can manifest as vibrations, pulsations, tickles, or changes in temperature.

Scientists have studied these sensations to establish a baseline for normal human perception. Understanding this baseline is important for clinical psychology. Some individuals, such as those with illness anxiety disorder, may interpret these normal physiological noises as symptoms of a serious disease. By mapping how and where these sensations occur, researchers hope to provide better data for therapeutic interventions.

Myrto Efstathiou, a researcher at The Open University, led the recent investigation. She collaborated with Louise S. Delicato and Anna Sedda from Heriot Watt University. The team sought to expand the scientific understanding of bodily awareness beyond the hands. Previous research has focused almost exclusively on upper limbs. This left a gap in knowledge regarding how we perceive other areas, such as the feet or the body as a cohesive unit.

The researchers also aimed to resolve a debate regarding the origin of these feelings. One theory suggests they arise from the bottom up. In this view, random firing of sensory receptors in the skin alerts the brain. Another theory proposes a top-down mechanism. This suggests that the brain’s internal representation of the body generates these experiences independent of sensory input.

To explore these questions, the team recruited 175 participants for an online study. They implemented strict screening criteria to ensure the results reflected typical physiology. Individuals with conditions known to alter bodily sensation were excluded. This included participants with restless leg syndrome or diagnosed skin conditions.

The study employed a two-part approach to measure spontaneous sensations. The researchers drew a distinction between “trait” and “state” experiences. This terminology borrows from anxiety research. It distinguishes between a person’s general disposition and their feelings at a specific moment in time.

The first task measured the “trait” level of sensation. Participants answered questions about their general tendency to experience phantom feelings. They reported the frequency and intensity of sensations in their hands, feet, and whole body. This relied on their long-term memory and semantic knowledge of their own bodies.

The second task measured the “state” level. Participants were asked to rest quietly for fifteen seconds. They closed their eyes and focused on their internal experience. Immediately following this brief period of rest, they reported any sensations they had just felt. This task was designed to capture real-time sensory processing.

In addition to measuring sensations, the researchers assessed visual attention. They used a standard psychological experiment called the Posner Cueing Task. This test measures a person’s ability to shift focus based on visual cues.

During the Posner task, participants watched a screen. Arrows appeared to indicate where a target object would likely appear. Sometimes the arrows were correct, and sometimes they were misleading. The speed at which participants reacted to the target allowed the researchers to calculate an attention score. The team hypothesized that individuals with higher attention skills might be more attuned to subtle bodily feelings.

The results of the study revealed a divergence between the trait and state experiences. When participants reported their general tendencies (trait), they described different levels of sensation across body parts. Specifically, they reported a stronger experience of spontaneous sensations for the whole body compared to the feet.

The reports for the hands fell between the whole body and the feet. The data showed that the whole body was perceived as having more frequent and intense sensations than the feet alone. This difference was statistically robust.

The researchers interpreted this finding through the lens of body representation. When people reflect on their body in a general sense, they likely access a “body image.” This is a top-down mental model. It appears that this mental model prioritizes the whole body as a coherent unit.

The representation of the feet appears to be weaker in this mental map. This may be because feet are less visually prominent in daily life. Unlike hands, which are constantly in our field of vision as we manipulate objects, feet are often covered or out of sight. This lack of visual familiarity might make it harder to recall their sensory history.

The results for the “state” task told a different story. When participants monitored their body in real time for fifteen seconds, the differences disappeared. There were no statistical differences in the intensity or number of sensations reported between the hands, feet, or whole body.

This suggests that immediate sensory processing is more uniform. When the brain monitors live signals from the body, it does not seem to rely on the hierarchical mental map used for memory. Instead, it processes the raw data from the somatosensory system. This indicates that the “ghost” sensations we feel in the moment may be driven by different mechanisms than the ones we remember feeling in the past.

The study also produced unexpected results regarding attention. The researchers divided participants into high and low visual attention groups based on the Posner task. They compared the sensation reports between these two groups.

The analysis showed no difference. Participants with high endogenous attention skills did not report more intense or frequent sensations. This held true for both the general trait assessment and the immediate state assessment.

This finding challenges some existing theories. Earlier work on the hands suggested that focused attention could amplify spontaneous sensations. The current data implies that the ability to voluntarily orient visual attention does not drive these experiences across the wider body. It appears that these bodily feelings may occur independently of our capacity to focus on external visual cues.

The authors outlined several caveats regarding their methodology. The study was conducted online rather than in a controlled laboratory setting. This increased the ecological validity, meaning it reflected real-world conditions. However, it also introduced uncontrolled variables.

For instance, the temperature of the room where a participant sat could influence their sensations. A cold draft might cause shivering or goosebumps. These physical reactions could be mistaken for spontaneous sensations. The researchers could not control for such environmental factors in participants’ homes.

The study also relied entirely on self-reporting. This method assumes that participants can accurately introspect and describe their internal states. It is possible that the explicit nature of the questionnaire prompted some participants to overestimate their sensations. The list of sensations provided was fixed, which may have prevented participants from reporting experiences that did not fit the given categories.

The demographic composition of the sample presents another limitation. The majority of participants were adults in their late twenties. Most identified as female. Previous research suggests that age and gender can influence bodily sensitivity. As a result, these findings may not fully apply to older adults or men.

Future research could address these limitations by using implicit measures. The authors suggest adapting tools like the Implicit Association Test. Such tests measure subconscious links between concepts. This could allow scientists to probe body representation without asking direct questions. This would help verify if the differences between whole-body and foot perception exist at a subconscious level.

This study provides a new perspective on how we perceive our physical selves. It highlights a split between our immediate sensory reality and our long-term body image. While our nerves may fire uniformly across different limbs, our mind prioritizes the body as a whole.

The study, “Ghost Sensations Across the Body: Trait and State Differences in Spontaneous Somatic Experience,” was authored by Myrto Efstathiou, Louise S. Delicato, and Anna Sedda.