I want to see the world.”-Designing an experiment“

Introduction

This study proposes an experimental design to address Molyneux’s problem by reviewing the relevant literature. The proposal aims to identify current unresolved issues and suggest a possible experimental test. To conduct the test, data will be analyzed using a t-test, following the methodology outlined in the module and informed by relevant research and literature.

Literature review

Molyneux’s Problem, first posed by William Molyneux in 1688, asks whether a person born blind can visually recognize objects previously known through touch (Degenaar & Lokhorst, 2017). Empirical studies provide insight by combining sight-restoration surgery with behavioral assessments. Held et al. (2011) and Sasaki et al. (1994) found that newly sighted individuals could not immediately integrate visual and tactile information, although single-modality recognition was possible. Hölig et al. (2023) highlighted structural limitations in visual cortex recovery. In contrast, Sinha et al. (2013) and Pedersini et al. (2023) suggested that neural plasticity remains after the critical period, with white matter reorganization supporting perceptual and behavioral gains. Mochizuki & Torii (1995, 2005, 2020) demonstrated that higher-order functions, such as stereopsis and depth perception, require extended learning and vary individually.

Theoretical debates examine the relationship between perception and cognition. Firestone & Scholl (2016) argue that perception is cognitively impenetrable, as prior tactile knowledge does not enable immediate visual recognition. In contrast, embodied cognition (Glenberg et al., 2013; Wilson, 2002) emphasizes dynamic interaction between bodily action and perceptual experience. Kahneman & Klein (2009) highlight that intuitive expertise is experience-dependent, and confidence alone does not guarantee accuracy. Pinker (2002) critiques the “blank slate” view, advocating for an integrated framework that includes evolutionary, genetic, and cultural factors. Versace et al. (2022) found that chicks can solve Molyneux’s Problem, suggesting innate mechanisms may support cross-modal recognition.

Despite these advances, current research has not fully resolved Molyneux’s Problem. Factors such as patients’ social background, individual experiences, education, and environment may influence outcomes (Pedersini et al., 2023; Sasaki et al., 1994), leaving the relationship between sight restoration, structural constraints, and individual differences unclear. Species differences between humans and birds are also acknowledged to be considered (Versace et al., 2022). Furthermore, principles of embodied cognition may enhance plasticity, suggesting that action-based learning could improve perceptual and cognitive recovery (Glenberg et al., 2013). Collectively, these gaps highlight the need for further investigation into how individual, structural, and experiential factors interact to enable sensory integration after sight restoration.

Building on this body of research, the next step is to design an experiment that systematically investigates how individual differences, structural constraints, and post-restoration learning interact to influence sensory integration, thereby addressing the gaps identified in previous studies.

Experimental Design

Purpose of the research:

The purpose of this research is to examine sensory integration outcomes following sight-restoration surgery using a longitudinal within-subjects design. Sensory integration performance will be assessed with a paired-sample t-tests in the same participants within 1 month post-surgery and again one year post-surgery, allowing for the evaluation of changes over time.

The study also includes an exploratory aim to identify individual, structural, and experiential factors that may contribute to variability in post-surgery outcomes. Individual factors include participant age at the time of surgery, structural factors include the presence of clinically documented brain damage, and experiential factors include the duration of blindness prior to sight restoration. These variables will be systematically recorded to characterize the sample. This study will conduct exploratory correlation and regression analyses to assess these associations, then suggest descriptive findings.

Paired-samples t-test:

Considering the purpose of this study, a paired-samples t-test is appropriate for comparing measurements taken immediately after cataract surgery and one year later. This test allows for the direct examination of changes over time within the same individuals.

One key advantage of using a paired-samples t-test is its statistical efficiency. In hypothesis testing, the required sample size is determined by the effect size (d) to be detected and the desired statistical power. An effect size of d = 0.2 represents a small effect. The significance level was set at α = 0.05, indicating an acceptable false-positive rate, and the statistical power was set at 0.8, meaning that if a true effect exists, there is an 80% chance of detecting it.

Under these conditions, power analysis shows that a paired-samples t-test requires approximately half the number of participants needed for an independent t-test to detect the same effect. This is because the paired-samples t-test controls for individual differences between participants, thereby reducing variability and increasing sensitivity to change.

Participants:

Participants will involve individuals who were born blind and have undergone sight-restoration surgery, similar to Project Prakash participants (Sinha et al., 2013). Demographic factors such as age, gender, ethnicity, and education level will be systematically recorded. Participants must be sufficiently mature to understand and respond reliably to experimental tasks (Held et al., 2011). They should have intact tactile abilities prior to surgery and restored visual input post-surgery, ensuring that touch and vision can be assessed as distinct sensory modalities.

Number of participants:
A power analysis indicated that, assuming a medium effect size (d = 0.5), a significance level of 0.05, and 80% power, a minimum of 34 participants would be required for a paired-samples t-test. Recruitment will be conducted through hospitals, social media advertisements, and collaboration with other researchers.

Ethical considerations:
The study will receive approval from the University of Auckland to ensure compliance with relevant ethical guidelines. Informed consent will be obtained from all participants. For participants under 18 years of age, consent will be provided by parents or caregivers. All assessments will be supervised by licensed medical professionals and course supervisors due to the complexity and sensitivity of this research.

Stimuli and Measures:

Each participant will be tested twice: once within 1 month post-surgery (Test 1) and once 1 year post-surgery (Test 2).
During each test, participants will be seated individually in a well-lit room and observe two objects placed on a table: a white ping-pong ball (sphere) and a wooden cube of the same size. Participants will not touch the objects but will be asked to describe what they see.

The same procedure will be applied for both objects and both time points, allowing direct comparison of each participant’s visual recognition ability immediately after surgery and one year later. All responses will be recorded by an observer to collect data for analysis. This paired design ensures that changes in performance over time can be attributed to visual experience rather than differences between participants.

The timing of assessments was chosen because Dormal et al. (2015) showed that behavioral and neurostructural improvements begin within 1.5 months post-surgery, with further improvements observed by 7 months.

Hypothesis:

Primary Hypothesis

H0 (Null hypothesis): Newly sighted individuals cannot match objects previously learned through touch with visual recognition better than chance.
H1 (Alternative hypothesis): Newly sighted individuals can match objects previously learned through touch with visual recognition better than chance.

The study predicts that congenitally blind individuals will not immediately transfer tactile shape knowledge into visual recognition after sight restoration, but with visual experience over time, they will develop increasingly accurate visual shape discrimination.

Secondary (Exploratory) Hypothesis

H2: Individual (age at the time of surgery), structural (presence of clinically documented brain damage), and experiential factors (duration of blindness prior to sight restoration) will collectively be associated with the magnitude of change in sensory integration performance.

 Data Analysis:

Data Preparation

Scores from Test 1 (within 1 month post-surgery) and Test 2 (1 year post-surgery) will be paired for each participant, and the difference between the two time points will be calculated. Responses for the sphere and cube will be converted into numerical scores to allow quantitative analysis. Any participant with missing data for either test will be excluded from the paired analysis to maintain data integrity. Data will be checked for normality and outliers before conducting statistical tests, as extreme values or non-normal distributions can affect the validity of the t-test.

Primary Statistical Analysis

The primary analysis will use a paired-samples t-test to compare Test 1 and Test 2 scores. This analysis will determine whether participants’ visual recognition ability has significantly improved over time. The significance level is set at α = 0.05. In addition to the p-value, Cohen’s d will be calculated to report the effect size, providing a standardized measure of the magnitude of change. Reporting effect sizes is important because statistical significance alone does not indicate the practical importance of the observed differences. This approach ensures that both the statistical and practical implications of the results are considered.

Secondary and Exploratory Analyses

To further understand factors influencing improvement in visual recognition, the study will include secondary and exploratory analyses:

1.             Correlation Analysis: Pearson or Spearman correlation coefficients will be calculated to examine whether factors such as age, duration of congenital blindness, or other demographic variables are associated with the degree of improvement. This analysis will help determine whether certain characteristics are linked to faster or slower sensory development.

2.             Regression Analysis: Linear regression models will be used to explore whether multiple variables together (age, gender, education, duration of blindness) predict the magnitude of visual improvement. These analyses will help identify which factors most strongly influence visual recovery and whether individual or structural characteristics moderate the relationship between time post-surgery and perceptual performance. Including regression analyses allows the study to control for confounding variables and better understand the relative contribution of each factor.

Data Visualization

Data visualization will be employed to enhance understanding and communication of the results. Line graphs will illustrate individual changes from Test 1 to Test 2, showing how each participant’s performance evolved over time. Box plots or bar graphs will summarize group-level trends, highlighting overall improvement and variability. Visual representation helps convey both individual and group-level findings clearly, making it easier to interpret the paired nature of the data and the extent of improvement.

Considerations and Limitations

With 34 participants, the study is adequately powered to detect medium to large effects (Cohen’s d ≥ 0.5), but smaller effects may not reach statistical significance. Differences in individual learning rates, familiarity with visual stimuli, or prior tactile experiences may introduce variability in results. In addition, the assessment environment, lighting, and object presentation may influence participants’ responses, so standardization of testing conditions is critical. While the paired design reduces inter-subject variability, caution is needed when generalizing results to broader populations.

Integration with Rehabilitation Strategies

This analysis plan not only evaluates visual recognition over time but also provides insights for practical applications. Understanding factors that facilitate or hinder cross-modal integration may inform rehabilitation programs. For example, identifying demographic or experiential factors associated with faster recovery could guide individualized therapy. Furthermore, combining visual training with embodied interventions, such as movement-based practices, may enhance both sensory and cognitive outcomes, supporting holistic rehabilitation.

Summary

This expanded analysis plan incorporates paired-samples t-tests, effect size reporting, and exploratory correlation and regression analyses. It also considers individual and demographic factors, environmental variables, and methodological limitations. By doing so, the plan ensures a comprehensive examination of sensory integration and perceptual development following sight restoration. This approach provides both theoretical insights into Molyneux’s Problem and practical guidance for designing effective rehabilitation strategies.

Conclusion and Future Directions

There are several complexities involved in addressing Molyneux’s problem and the unresolved issues. However, this study represents the first attempt to design a t-test and analyze data in this context. The topic proved more complicated than initially expected.

For future research, it will be important to enhance embodied cognition and neuroplasticity to achieve better outcomes after sight restoration. Improvements may be possible when considering individual differences, such as adverse childhood experiences, social background, living environment (Sinha et al., 2013), intellectual ability (Sasaki et al., 1994), and brain impairments (Hölig et al., 2023).

These findings suggest that embodied interventions, such as dance-based mindfulness practices, may provide promising strategies for supporting sensory integration and cognitive development. A recent scoping review of dance-based interventions showed that programs combining movement with mindfulness or somatic awareness—including Dance/Movement Therapy (DMT), ballet-yoga combinations, and community-based mindful movement—were associated with improvements in body awareness, emotional regulation, stress reduction, self-compassion, and social connection in non-clinical populations (Zafeiroudi et al., 2025).

Although the evidence base is still limited, movement-centered mindfulness practices can increase interoceptive awareness and psychosocial resilience, while being feasible and acceptable outside clinical settings. Applying these findings to sight-restoration rehabilitation, embodied approaches may enhance the connection between body, mind, cognition, and behavior, potentially stimulating neuroplasticity and supporting adaptive sensory processing. Integrating dance-based mindfulness or other embodied practices into post-surgery rehabilitation may complement traditional visual training, offering a holistic approach to sensory and cognitive development.

References

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Dormal, G., Lepore, F., Harissi-Dagher, M., Albouy, G., Bertone, A., Rossion, B., & Collignon, O. (2015). Tracking the evolution of crossmodal plasticity and visual functions before and after sight restoration. Journal of Neurophysiology, 113(6), 1727–1742. https://doi.org/10.1152/jn.00420.2014

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Pedersini, C. A., Miller, N., Tapan Kumar Gandhi, Gilad-Gutnick, S., Mahajan, V., Sinha, P., & Bas Rokers. (2023). White matter plasticity following cataract surgery in congenitally blind patients. 120(19). https://doi.org/10.1073/pnas.2207025120

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