Perception of Temporal Patterns Dirk-Jan Povel & Peter Essens University of Nijmegen, The Netherlands

Overview Nature of Temporal Patterns The Model Experiments Experiment 1 – Prediction Experiment 1 – Prediction Experiment 2 – Internal Clock Experiment 2 – Internal Clock Experiment 3 – Double Sequences Experiment 3 – Double Sequences Conclusion and Future Work Perception of Temporal Patterns 2/11

Comprise a special class of serial patterns -Collard & Povel, Deutsch & Feroe, Leeuwenberg, Restle, Simon, 1972 Symmetry is not perceived -Mach, Restle, 1976 Do not form alphabets -Coding models using in serial patterns can’t use in temporal patterns Special Nature of Temporal Patterns Perception of Temporal Patterns 3/11

The Model Internal Clock Absolute clock Absolute clock Unit derived from the sequence Unit derived from the sequence Hierarchical clock Hierarchical clock Unit (interval between ticks) Location (synchronization) One period Pattern Clocks Unit Location Perception of Temporal Patterns 4/11

Accent Isolated tones Isolated tones The second tone of a cluster of two tones The second tone of a cluster of two tones The initial and final tones of a three or more tones cluster The initial and final tones of a three or more tones cluster The Model (cont.) one period <<<<<< Sequence : Perception of Temporal Patterns 5/11 Selection of clocks

The Model (cont.) Best Clock C: amount of counterevidence C: amount of counterevidence ev: accented event, 0ev: unaccented event, -ev: silent event C = (W* -ev) + (1* 0ev) C = (W* -ev) + (1* 0ev) Sets of patterns Categories 1: Categories 2,3,4: Categories 5,6,7: Categories 9: < <<<<< Combination of : <<<<<< (C3) <<<< <<< <<<<<< (C7) Perception of Temporal Patterns 6/11

Coding the temporal structure S : If clock unit is subdivided into equal intervals S : If clock unit is subdivided into equal intervals E : If clock unit is empty E : If clock unit is empty N - N : If clock unit is subdivided in unequal length N - N : If clock unit is subdivided in unequal length The Model (cont.) Example: Pattern Clock Unit Location Code S 2, S 4, S 2, E, E, S 2, S 2, E Perception of Temporal Patterns 7/11

Experiment 1 35 sequences from the combination (5 from each of seven categories) Reproduce these sequence by 24 subjects *Higher categories will have worse reproduction **Strength of induction plays a crucial role Perception of Temporal Patterns 8/11

Experiment 2 20 sequences and same subjects from the previous experiment Reproduce the sequence after hearing a patterned sequence 830 Hz 125 Hz **The reproduction improves with the additional induction of an internal clock Perception of Temporal Patterns 9/11

Experiment 3 12 pairs of two double sequences Compare each pair of sequences by 25 subjects 3 - clock4 - clock Perception of Temporal Patterns 10/11 **temporal structure is coded in units of the clock Sequence Nonreducible Intervals (3-clock) (4-clock) …

Conclusion and Future Work A given temporal pattern will be poorly reproduced (Expt.1, Expt.2) or be judged (Expt.3) when either no internal clock is induced or the coding is complex. The internal representation of a pattern completely depends on the clock which is internally induced. Clock-selection mechanism Further analyze in coding characteristics Determine the contribution of decoding in the production of temporal patterns Perception of Temporal Patterns 11/11