A critical function of perception is the organization of temporally spaced input. This is accomplished through grouping, a process by which within-group elements are integrated with one another to form a cohesive unit. Grouping also requires boundaries to set off within-group elements from unrelated stimuli. In the temporal domain, grouping may be accomplished through use of an implicit working memory system that connects temporally spaced information. Temporal group boundaries may be created by reductions in the default integrative processes of this memory system. The present experiments probed integration strength by embedding priming tasks within temporal groups (i.e., events). Because priming also draws upon implicit working memory, priming strength should reflect the strength of integration. If modulation of temporal integration is responsible for grouping, this should be manifested as a reduction of priming across boundaries. Irrelevant feature priming tasks were used to assess integration strength. Participants responded to one of two independently varying object features. In this form of priming, change consistency of relevant and irrelevant features produces faster reaction times, resulting in a crossed interaction. This interaction served as a meter for the strength of temporal integration. The experiments included a variety of temporal grouping manipulations. Experiments involving rhythmic groups, spatial shifts, rotations, pitch, and timbre, as well as higher-level conceptual shifts, demonstrated reduced priming in across-boundary conditions. Both visual and auditory events were used, and experiments demonstrated that viewers’ interpretation of a scene contributed to the observed effects. Temporal integration does appear to be reduced at certain event boundaries, suggesting that this may be the general manner in which temporal grouping is accomplished. Motion change, a boundary from event segmentation research, did not reduce priming, indicating that the process presently under study differs from that studied using explicit segmentation procedures. The reduction of integration may correspond to a subjective, amodal experience of separation. The present technique may therefore offer an objective, implicit method to assess this sense of separation. Using this method, it is possible to reliably determine when people are experiencing temporal group boundaries even when they are not deliberately attending to them. / text

[Truncated abstract] Various capabilities such as the ability to read or conduct a conversation rely on our ability to maintain and recall information in the correct order. Research spanning more than a century has been devoted to understanding how units of information are retained in order in short-term memory. The nature of the mechanisms that code the positions of items in serial short-term verbal recall can be investigated by examining a set of phenomena that can be termed temporal grouping effects. Inserting extended pauses to break a list of verbal items into sub-lists (e.g. SHD-QNR-BJF, where the dashes represents the pauses) improves the accuracy of serial recall relative to performance observed without this temporal grouping. In addition, two other effects are linked to temporal grouping. One of these effects is a shift in the shape of the serial position function, which changes from a single bowed function to a multiple-bowed function. That is, the serial position curve for ungrouped sequences is typically characterized by better performance for the beginning and ending items compared to the mid-list items. For grouped lists, the multiple-bowed function comprises better recall for the beginning and ending items within each group. Another effect associated with temporal grouping is a change in the patterns of order errors. For ungrouped sequences (e.g. SHDQNRBJF), order errors often involve the swapping of items in neighbouring positions, such as exchanging D for Q or R for B. By contrast, grouped sequences (such as SHD-QNR-BJF) show a reduction in order errors that cross group boundaries such as exchanging items D and Q or R and B; instead, there tend to be an increased incidence of exchanging items that share similar within-group positions such as swapping H and N or Q and B. According to several current models of short-term memory, items are retained by associating them with extra-list information such as contextual information. ... This was done by unconfounding temporal position (time from group onset) and ordinal position (number of items from group onset) for certain key items in sequences comprising two groups of four consonants. The critical manipulation was to vary the SOAs within and across the two groups. Errors that involve items migrating across groups should preserve within-group temporal position according to oscillator models, but should preserve within-group ordinal position according to non-oscillator models. Results from the intergroup errors strongly favored preservation of ordinal rather than temporal position. Finally, the Appendix reports an unpublished experiment that examined patterns of errors in recalling sequences of nine visually presented letters, where the letters were grouped into threes using temporal gaps. A critical manipulation was the insertion of a tobe- ignored item (an asterisk) between the first and second letters of selected groups. Inclusion of this item failed to alter the patterns of errors observed, indicating that the coding of serial position is based on only those events represented for recall. The central conclusion based on all the studies is that serial order for verbal items is retained using contextual positional codes that change with each presentation of a tobe- remembered item, are influenced by large temporal gaps that lead to grouping, but otherwise are not dependent on the timing of events.