We get off the train in Padua, the last station of our trip, where we meet

Silvia De Marchi


Piazza Capitaniato, Padua

In Corte Capitaniato, today Piazza Capitaniato, Padua, in the buildings of the School of Philosophy, the psychology laboratory rooms were crowded with students and researchers. The laboratory was founded by Vittorio Benussi in 1919 at his home, “in a lonely little room by the river”. In eight years it became one of the best equipped and productive laboratories in Italy.

Silvia De Marchi began working in Benussi’s laboratory as an undergraduate student. In her short life, she conducted relevant research in perceptual psychophysics and forensic psychology.

She applied the method of magnitude estimation to scale visual numerousness, a few years before Lewis Richardson, who is currently believed to have been the inventor. She was also presumably the first to graphically plot a psychophysical function obtained by this method (Masin, 2012).


The instruments in the psychological laboratory built up by Benussi in Padua

courtesy of ASPI, the Historical Archives of Italian Psychology

De Marchi published a series of experiments on visual numerousness in 1929. She presented different configurations of dots (from 5 to162) to the subjects (n≥5), for a very short time so as to prevent the counting of dots, and asked them to numerically estimate the numerousness of dots. Magnitude estimation requires an absolute judgment of numerousness in each dot pattern; the alternative method of relative judgment requires a comparison between patterns.

“we instead consider the laws of evaluative errors in the case in which one has not yet learned to adequately evaluate and it is not possible to learn because the subject has not ever had knowledge of his errors”.

Compared to previous studies performed by Liebenberg in 1914 and Mokre in 1927, De Marchi used a greater number of dots, different exposure times, and different spatial arrangements (ordinary geometrical shapes and amorphous sets of dots).

She evaluated fixed dot configurations in the static experiments, and dot configurations in motion, in the dynamic experiments. The method of presentation of dot configurations was tachistoscopic, that is, by projecting the stimuli on a screen very briefly. She used an Ernemann projector that allowed projections with a  side length spanning from a few centimeters to several meters. The lamp of the projector was activated by a circuit that, among other elements, consisted of a metallic pen and a kymograph. This made it possible to illuminate slides for different durations with exposures times from 200 to 8000 milliseconds or more.

In some cases the subjects were overestimating the number of dots and in other cases they were underestimating. These variations were subject-based: “the overestimation or underestimation are real “individual constants””. De Marchi found that the mean value for overestimates and underestimates was nowhere near the real number of dots and, generalizing these findings, advised courtroom judges to be careful in evaluating information from different witnesses.


Examples of the stimuli and apparatuses used by De Marchi for the numerical evaluations of collectivities

courtesy of the Historical Archive of the University of Padua

De Marchi observed the interactions between internal factors, representing the “awareness behavior” of the subjects towards the stimuli, and external factors, given by the objective conditions in which the stimuli were presented. Manipulating the exposure time, the perceptual vividness, the area of the dots, the shape and size of the patterns, the dot density, and the spatial and temporal arrangements, she observed stable and specific effects on the subjects’ estimations. As an example, for small sizes of the area of the pattern of dots, the lower density of dots was a determinant of overestimation, whereas for large sizes, the lower density was a determinant of underestimation.

Examples of the absolute magnitude estimation curves in the De Marchi’s thesis 1924:







The paper published by De Marchi in 1929 was an excerpt from her graduate thesis (1924). This was the first thesis produced in the psychology laboratory at the University of Padua, as stated in a lovely letter of congratulations from the staff.

Another part of the thesis was dedicated to forensic psychology.

She conducted substantial experimental research on respiratory patterns in deception, applying the “inspiration-expiration ratio” introduced by Benussi to assess the credibility of witnesses.

De Marchi, to explain the multiple influences on individual judgments and estimations, also mentioned that the first person that provided a scientific explanation of the moon illusion was Benedetto Castelli. A drawing she made shows the comparison with reference objects of known size:


De Marchi urged the introduction of objective measures to assess the reliability of witnesses in the court.

“Considering the value of a testimony, in relation to the memory of a fact, we have reported some experiences to prove that memory is almost deceiving and that an absolute persuasion is not an index of correspondence with reality”.

She hypothesized that if an event is reported with a certain concordance in its details, this may depend not only on the fact that all witnesses observed the same things, but it may also depend on the fact that a uniformity of reaction to certain events and a uniformity of memory errors exists among all these witnesses, especially if they are part of the same environment. A concordance of court depositions can be due to the observation of a fact as it actually happened, as well as to a reactive consistency of illusion in response to a given order of elements.


The respiratory curve for the experience of lying, 1924
The respiratory curve for the experience of sincerity, 1924

In 1914, Benussi introduced the ‘respiratory diagnosis’, based on the analysis of the traces of a pneumograph, for assessing the reliability of witnesses, instead of trusting them based on subjective criteria. He found that if the ratio of the duration of inspiration to the duration of expiration was generally greater before a person was being truthful than afterwards, and greater after lying than before lying.

According to De Marchi the respiratory diagnosis was more reliable than trusting witnesses based on subjective criteria. She believed that the respiratory patterns did not depend on being sincere, but rather on the awareness of lying or telling the truth.

She claimed that, even if the breath amplitude could be deliberately modified by the subject, this would not significantly alter the respiratory curves. On the contrary, when lying, the ratio between length of inspiration and length of expiration increases after the subject makes a statement, whereas in truth-telling this same ratio decreases after the statement is pronounced.

Later studies revealed that the inspiration-expiration ratios were inconclusive. Notwithstanding, the research on respiratory diagnosis conducted in Padua is now part of the history of lie detection.

Silvia De Marchi conducted original and interesting experiments on forensic psychology, as well as on magnitude estimation and they are worth being recalled today.


Silvia De Marchi

Biography. Silvia Igilda Maria De Marchi was born on February 25, 1897, in Pavia, by Rosa Porro and Luigi De Marchi, professor of physical geography. She had five brothers: Giovanni, Giulio, Vittorio, Iginio, and Emilio and one sister, Lucia. In 1902 the family moved to Padua, where Luigi was appointed full professor. Silvia De Marchi completed her high school studies at the Liceo Classico Tito Livio in 1918. In 1919, she began to study philology, literature and history at the University of Padua, and in 1920-21 she began to attend the laboratory of experimental psychology established by Vittorio Benussi.  Soon after joining the lab, she requested to continue her studies at the School of Philosophy, and her request was accepted after one year and many letters between the President of the University and the Ministry of Education. She graduated in Philosophy in 1924 with a thesis on the experimental contribution to forensic psychology. Her preliminary work was presented by Benussi at the IV National Congress of Psychology in Florence in 1923, when De Marchi was an undergraduate. The proceedings of the congress report that Benussi read De Marchi’s paper to the audience.

On October 16,  1925 she was appointed voluntary assistant at the psychology laboratory, continuing after Benussi’s death in 1927. From 1929 to 1932 she was intern at the Institute of Experimental Psychology, under the direction of Cesare Musatti. In November 1929, she participated at the VII National Congress of Experimental Psychology and Psychotechnic in Turin with a talk entitled “Percezione di forma e impressione di quantità: sopra un caso particolare della figura di Müller-Lyer [Shape perception and impression of quantity: a particular case of the Müller-Lyer figure]”. In 1932 she married Cesare Musatti. They had one child, Riccardo.

In 1935 she had a miscarriage due to infection and fever. She died a few months later of mastoiditis.



We gratefully acknowledge the continuing assistance of Paola Zocchi at ASPI, the Historical Archives of Italian Psychology and the kind support of Marco De Poli, and Donatella Mazzetto at the  the Historical Archive of the University of Padua. We are grateful to Sergio Masin. Thanks to Sadi Marhaba and Massimo Grassi.



To cite this profile, please use the following format:

Metitieri, T., Mele, S. and Favero, M. (2017). Profile of Silvia De Marchi. In WiNEu, European Women in Neuroscience, Untold stories: the Women Pioneers of Neuroscience in Europe. Retrieved from


Selected work

  • De Marchi S. (1923): La valutazione di collettività [Evaluations of collectivities]. Atti del IV Congresso Nazionale di Psicologia Sperimentale, Firenze: Stab. Tip. Bandettini: 131-134.
  • De Marchi S. (1929): Le valutazioni numeriche di collettività [Numerical evaluations of collectivities]. Archivio Italiano di Psicologia 7, 177-225.
  • Musatti De Marchi S. (ed.). (1932): Suggestione e psicanalisi / Vittorio Benussi [Suggestion and Psychoanalysis / Vittorio Benussi]. Messina-Milano: Principato.


  • Archivio Storico della Psicologia Italiana (ASPI) [Historical Archives of Italian Psychology]. Silvia De Marchi 
  • Masin S.C. (2012): A brief trip into the history of psychophysical measurement. Proceedings of Fechner Day 28: 162-167.
  • Metitieri T. (2016): Toletta con chimografo [Dressing table with a kimograph], CreateSpace Independent Publishing Platform.