Peter Cariani, Ph.D.

Neural timing nets
Adaptive systems
Temporal codes
Music perception
Theoretical biology
Artificial life
Philosophy of mind
Other topics

The Prisoner: dark, contrasty photo

Electronic coordinates

email  addresses
 (omit the numbers from the address)


  Picture of myself at the Trevi Fountain


Upcoming events (January 2011)

This spring I  will be teaching a Harvard Mind Brain and Behavior Initiative seminar entitled "Music, Mind ,and Brain" (MBB91). My newly revamped website will include study materials from that course and some discussion of topics in the psychology of music.

I will also be giving two two-hour lectures at MIT during the Independent Activities Period (IAP) entitled "A Crash Course in the Neuropsychology of Music" on Wednesday, January 11th and January 18th, 7-9 PM, MIT room 56-114.

Site update: December 6, 2011

I am currently updating this website and preparing to migrate it to a more stable server (please be patient, hopefully these changes will be implemented this week). Here is a link to the new website.

I want to improve the overall organization of the site and update its content.

Recent papers 2009-2011
To be uploaded soon.

I am currently working with Ramdas Kumaresan, Professor of Electrical Engineering at the University of Rhode Island, on auditory-inspired representations and signal processing operations for auditory scene analysis. We are currently working on synchrony-capture adaptive filter banks that are based on temporal coding of lower-frequency sounds in the auditory nerve (PDF to be uploaded soon).


In 2009 I edited a book by Yoichi Ando on architectural acoustics that is grounded on psychological and neurophysiological observations of listener percepts and preferences (Auditory and Visual Sensations, Springer, November, 2009).

Ando's approach is a rational theory of design that optimizes concert hall shapes based on acoustical models, psychoacoustics of auditory percepts, and  measured listener preferences.

I believe that Ando is also unique in taking architectural acoustics inside the listener by measuring and modeling the neural processes involved in the listener's percepts and preferences.

Lastly (as if this were not enough in and of itself), Ando and his co-workers have applied the same correlation-based approach to simple visual percepts and preferences (temporally-modulated light, oscillating forms, and spatial textures).

The book is available through Springer, Amazon, and the usual outlets in print and e-book formats (Google Books link). Here is a presentation of the book that I gave at Boston University. (PDF).

A shorter, 40 page concise outline of Ando's theory will appear in a forthcoming Springer volume commemorating the late Manfred Schroeder.

Image of the cover of Ando & Cariani book.


Workshop paper on "Designing for Open-Ended Evolution" (PDF).

Scholarpedia article on "The Jeffress Model". (PDF)   Article in progress, comments are welcome.

Presentation to session on “Flattening Federal research funding: The local angle”, Annual meeting of the Association of Health Care Journalists, Alexandria, VA,  Friday, March 28, 2008, "The NIH Flat-funded: A view from the ground level. (PDF).


Symposium on "Creativity: The Mind, Machines, and Mathematics", MIT Stata Center, November 30-December 2, 2006, sponsored by the Templeton Foundation. My working paper for this discussion: "On creating new infomational primitives in minds and machines", PDF.

I am still very much interested in the neural coding problem, temporal codes, neural timing nets, auditory neurocomputation, auditory scene analysis, the neural representation of pitch, and the neural basis of music perception. 

I firmly believe that if we are to successfully understand how the brain works as an informational system, we need to understand the precise nature of the pulse-coded signals it uses. The neurosciences desperately need to address problems of neural coding head-on, and we need to contemplate neurocomputational alternatives to rate-codes and traditional connectionist networks. One can glimpse the power of temporal pulse codes and computations that could permit neural signals to be liberated from dedicated transmission lines, much in the same way that radio and internet have transcended telegraph networks. The high dimensionality of temporal pattern codes affords more flexible means of implementing type-based logics in neural networks. I am interested in seeing these new kinds of temporal processing networks become a reality; please contact me if you know of persons or organizations interested in funding such paradigm-shifting work.

In the Fall of 2003, Spring of 2004, and this past semester, I had the privilege of organizing and teaching courses on music perception and cognition at Tufts University and MIT. I will be teaching 
HST 725 Music Perception & Cognition again this spring at MIT, TR 7-9 PM, E25-101. The MIT course, HST 725, has an OpenCourseware website from 2004 that is freely accessible to all (URL below). A good deal of new material was been added for 2007 (email me if you are interested in current course content).

As a personal favor to Mary McKinnon, who taught my son piano until serious illness intervened, I have scanned The Capture of Imagination by her mentor, E. Robert Schmitz. The book, published in 1935 by Carl Fischer and long out of print, is a rational theory of piano performance based on the mechanics and kinematics of human and instrument. Mary is one of the last surviving students of Schmitz, and she is writing a commentary on his pedagogical method. Our understanding is that the publisher has no current interest in reprinting the work, and does not mind if an electronic copy is made freely available to the world. PDF and .doc formats can be downloaded:  Schmitz (1935, pdf, 32.4 Mb).


Recent papers and events

Publications: with links to viewable and downloadable documents

NSF-BITS Project Site

Neural coding and related issues

Temporal coding clearinghouse: collating evidence from different modalities and systems.

The problem of neural coding:

            Which aspects of neural response convey functionally-relevant information?
            Patterns of spikes vs. patterns of channel-activations

Temporal coding of sensory information:

 As if time really mattered: temporal strategies of sensory coding (1995)

     (Download pdf format, 204k)

            General theory and examples from different modalities
            The many consequences of phase-locking
            Extrinsic, stimulus-drive time structure vs. intrinsic, stimulus-evoked time structure

Auditory neurophysiology

Temporal coding of pitch and timbre in the auditory system:
            Population-interval representations in the coding of pitch (pdf)
            Population-interval distributions and autocorrelation (pdf)

Temporal discharge patterns in the auditory nerve. When a periodic sound is presented to the ear, it impresses its own temporal structure on the discharges of auditory nerve fibers. As a consequence of this stimulus-driven time structure, there exist correlations between timings of spikes and the stimulus waveform ("phase-locking"). In this case the stimulus is a single-formant vowel, with a fundamental frequency of 80 Hz and most spectral energy in harmonics near 640 Hz (formant frequency), presented 100 times at 60 dB SPL. The stimulus produces a strong "voice pitch" at its fundamental, and this periodicity can be seen in the discharge patterns of auditory nerve fibers across the auditory nerve array. When time durations between both successive and nonsuccessive spikes are tabulated in an interspike interval histograms, intervals related to the fundamental period (pitch period) and to spectral shape (tone quality, timbre) are seen. For harmonic stimuli, the most frequent intervals in the auditory nerve are those associated with the fundamental, such that the pitch that is heard invariably corresponds to the most frequent interspike interval. Exceptions to this rule involve stimuli that produce buzzy, rate-pitches an octave above the fundamental as well as some subtle pitch shifts that can occur with large changes in level.

The figure on the right shows two possible neural representations of the stimulus. The two plots on the left show the  power spectrum of the vowel and the average firing rates of auditory nerve fibers as a function of their characteristic frequency. Average rate information from this number of fibers is not sufficient to identify the frequencies of individual harmonics in the stimulus that would be necessary to support a spectral pattern analysis of pitch. The plots on the right show the stimulus autocorrelation function and the population-interval distribution formed by summing all-order intervals from all fibers (i.e. the interval statistics of the whole auditory nerve). The population-interval distribution constructed from the responses of these fibers contains on the order of 100,000 intervals, and is sufficient to estimate the fundamental frequency (1/F0) with ~1% accuracy. This is in the ballpark of the ability of humans to detect changes in pitch on the order of fractions of a percent. A major advantage of interval codes over rate codes is that representations of stimulus periodicities remain highly invariant over a very wide dynamic range.


Neural coding and stimulus equivalence: an example of psychoneural isomorphism. Neural responses to four stimuli evoking a pitch at 160 Hz but differing in pitch salience. Left to right: Stimulus waveform, power spectrum, short term autocorrelation function, and population-interval distribution for each stimulus. Population-interval distributions are constructed by summing together the all-order interspike interval distributions of many auditory nerve fibers (n=49-85) having a wide range of characteristic frequencies. These interval distributions share a common feature: the most frequent interspike intervals present correspond to the pitch period and its multiples. While the top four stimuli give rise to strong definite pitches, the bottom two evoke weak, more diffuse pitches. Pitch salience qualitatively corresponds to the fraction of pitch-related intervals in the whole interval distribution (quantified in terms of peak-to-mean ratios in the distribution).

Coding of pitch in the cochlear nucleus

Coding of pitch in the auditory cortex

Temporal coding and speech perception
    Towards an temporal theory of speech perception
    Similarities and differences between autocorrelation and modulation detection operations
    Formant structure
    Voice pitch
    Voice onset time
    Temporal cues associated with frequency shifts
    Envelope dynamics
    Implications for cochlear implants
    Implications for speech recognition
        Interval-based front-ends for speech recognizers
        Running summary autocorrelations as alternatives to spectrograms
       Autocorrelation-based recognition strategies

Neural substrates of music perception

Cariani, P. (2004). A temporal model for pitch multiplicity and tonal consonance. Proceedings, Int. Conf Music Perception  & Cognition (ICMPC), 4 pp., Evanston, IL,  August 3-8, 2004.

P. Cariani. (2001). Temporal codes, timing nets, and music perception. J. New Music Research.

Tramo, MJ, Cariani, PA, Delgutte, B, Braida, LD. 2001 Neurobiological Foundations for the Theory of Harmony in Western Tonal Music. Annals, New York Academy of Sciences, vol 92, pp. 92-116 (PDF, 8.9 Mb).

Temporal coding and music perception
    Pitch and timbre
    Tonal fusion
    Harmonic relations
    Autocorrelation-based model of tonal context (e.g. Krumhansl note-key correlations)
    Rhythm (pdf working paper on timing nets and rhythm)

Neural timing nets

P. Cariani. (2001a). Neural timing nets. Neural Networks, in press. (Uncorrected proofs, pdf)

P. Cariani. (2001b). Neural timing nets for auditory computation. In S. Greenberg & M. Slaney (Eds.), Computational Models of Auditory Function (pp. 235-249). Amsterdam: IOS Press.

P. Cariani. (2001). Temporal codes, timing nets, and music perception. J. New Music Research (in press).

Neural timing nets for utilizing temporally-coded inputs:
            Extraction of similarities, buildup & separation of objects

Neural computations in the time domain (ARO1998 poster)
View as HTML webpage
Download pdf file

Auditory object formation through temporal coherence (ARO2000 Poster, in pdf format)

    Extensions of timing networks to frequency-by-frequency analysis

Discussions of high level integration of neural information
    Signal multiplexing, emergence of new signal-primitives, broadcast models of coordination (pdf, 204k)

Regenerative processes (pdf, 68k)

Closing the loop: common time structure in perception and action

Relational alternatives to feature detection, perceptual atoms, and decision trees (thinking in progress)

Adaptive systems

Towards an evolutionary robotics:
    a taxonomy of adaptive systems (Short paper, pdf)

    Purely computational devices
    Robotic devices with fixed sensors, effectors, and coordinative faculties
    Robotic devices with adaptive coordinative faculties
    Robotic devices with adaptive sensors and/or effectors
      • Gordon Pask's adaptive electrochemical device
    Self-constructing, self-modifying evolutionary robotic devices
    Epistemic autonomy: systems that determine their own categories vis-a-vis the environment

• Cariani P. On the design of devices with emergent semantic functions. Ph.D. Thesis, State University of New York at Binghamton, 1989; 234 pp. Download pdf file (7 Mb)

Theoretical biology, biological cybernetics, biosemiotics, epistemology

Theoretical biology
    • Links to other theoretical biology sites (forthcoming: Pattee, Rosen, Kampis, Conrad, Emmeche, Moreno & others)
    • Bibliography of theoretical biology
    • Interview with Robert Rosen on the evolution of his ideas
        (VHS-NTSC, 2 hrs, April, 1998, available upon request)

• Cariani, P. (1991) Emergence and artificial life. In: Artificial Life II,  SFI Studies in the Sciences of Complexity, vol X, edited by C.G. Langton, C. Taylor, J.D. Farmer, & S. Rasmussen, Addison-Wesley, pp. 775-796. (Download pdf, 9 Mb)

Commentary on Cybernetics, Connectionism and Hayek's Sensory Order : CarianiOnSmith.html

Semiotics of adaptive devices (pdf)
Meaning-construction and the semiotics of communication (abstract and pdf)


    Observer-mechanics: operational structure of scientific models (Hertz, Bridgman, Bohr)
    Semiotics of scientific models (Cassirer, Morris)
        Measuring devices implement external semantics of model states
        Formal procedures (computations) implement syntactic relations
        Choice of observables to be predicted determines pragmatics of the model
            Pragmatic operations involve change of measurements and/or formal procedures to realize better prediction
            Systems that construct and/or choose their own observables
    Recognizing symbols in natural systems
    Recognizing computational processes in natural systems
    Embedding modeling relations in natural systems: percept-action loops
    Towards a pragmatist evolutionary epistemology

The problem of the emergence of new functions
    Combinatoric conception of emergence: (ontological in orientation)
        Logical combinations of fixed set of primitives: concatenation & recombination
        Limitations of searches on closed possibility-spaces
    Emergence of new primitives: (epistemological in orientation)
        Emergence-relative-to-a-model: observers with partial descriptions
        Adaptive devices and functional emergence
       Emergence in neural networks (download pdf file)

Philosophy of mind: an organizational basis for conscious awareness
 Regenerative process in life and mind
    Regenerative processes in living organization: autopoiesis, self-reproduction
    Regenerative, buildup processes in neural signaling
    Process-coherence theories of neural integration and neural substrates of awareness
        (vs. neural specificity or special process accounts)
    Hylomorphic conceptions of mind-brain relations: coherent organizations embedded in matter
    Psychoneural isomorphism: organization of neural information processing isomorphic to structure of experience
    Observer-mechanics and the structure of awareness
        externally-originated, contingent signals experienced as sensations
        internally-produced signals experienced as thoughts
     General anesthesia as a test-bed for the neural substrates of conscious awareness
        General anesthetics do not abolish neural activity altogether
        Some general anesthetic agents increase neural discharge activity in many parts of
            the brain (e.g. chloralose)
        A very wide range of agents can act as general anesthetics when they
            reach sufficient concentrations in (lipid layers of) cell membranes (Meyer-Overton)
        All general anesthetic agents disrupt the coherence of neural firing patterns
            by altering relative firing rates and/or by altering temporal recovery processes

Psychoneural isomorphism: neural codes and the structure of perception (colloquium abstract)

An operationalist perspective on the foundations of mathematics
 Construction of sets by enumeration vs. by implicit definition
    Platonic vs. constructivist modes of operation
    Free thought-creation vs. verifiability: realms of imagination vs. demonstrable proofs
    Critiques of infinity and the continuum
        (Aristotle, Leibnitz, Kronecker, Brouwer, Weyl, Goodman, Wittgenstein)
    On the irrelevance of Godel's Theorems for physically-realizable systems
        (consistency of finite systems is always decidable within a finite number of steps)
    Reading list


Preserving alternative visions of the future: social institutions that enhance human dignity
The Mondragon industrial cooperatives: worker-owned, worker-controlled enterprises in a free-market  framework
Gramin Banks: bottom-up economic development
Waiting for the Big One : 1) is the world financial system inherently stable?
                                            2) long economic waves and dynamical systems, is Kondratieff really dead and gone?