The whole moves less than the spin of its parts

When individually moving elements in the visual scene are perceptually grouped together into a coherently moving object, they can appear to slow down. In the present article, we show that the perceived speed of a particular global-motion percept is not dictated completely by the speed of the local moving elements. We investigated a stimulus that leads to bistable percepts, in which local and global motion may be perceived in an alternating fashion. Four rotating dot pairs, when arranged into a square-like configuration, may be perceived either locally, as independently rotating dot pairs, or globally, as two large squares translating along overlapping circular trajectories. Using a modified version of this stimulus, we found that the perceptually grouped squares appeared to move more slowly than the locally perceived rotating dot pairs, suggesting that perceived motion magnitude is computed following a global analysis of form. Supplemental demos related to this article can be downloaded from app.psychonomic-journals.org/content/supplemental.     

The rod-and-frame effect: the whole is less than the sum of its parts

Since the discovery of the influence of the tilted frame on the visual perception of the orientation perceived as vertical (VPV), the frame has been treated as a unitary object-a Gestalt. We evaluated the effect of 1-line, 2-line, 3-line, and 4-line (square frame) stimuli of two different sizes, and asked whether the influence of the square frame on VPV is any greater than the additive combination of separate influences produced by the individual lines constituting the frame. We found that, for each size, the square frame is considerably less influential than the additive combination of the influences of the individual lines. The results conform to a mass action rule, in which the lengths and orientations of the individual line components are what matters and the organization of the lines into a square does not-no higher-level Gestalt property is involved in the induction effect on VPV.     

Divided attention: the whole is more than the sum of its parts

A divided attention situation is more than the sum of its component single tasks. Emergent aspects of the whole situation must also be considered. Three examples illustrate this. (a) When several complex stimuli (e.g., letters) are identified at once, their perceived components or features must be appropriately bundled together. Otherwise, components of two different stimuli may appear combined. This (emergent) problem is shown to depend on attention to multiple stimuli, not simply their presentation. (b) In the psychological refractory period (PRP) situation, especial difficulties arise when stimulus-response mappings are different for first and second reactions. It appears that for each reaction there is some (emergent) uncertainty over which mapping to use. This is only one of many possible emergent processes in the PRP situation. (c) When the two hands perform different actions (internally programmed sequences of taps), there is some tendency for each hand to carry out the action assigned to the other. This again is only a small part of the (emergent) problem of motor coordination. Thus the simple idea of competition for limited resources captures only a part of the problem of divided attention. Performance under divided attention will reflect an interaction between resource limitation, single task processes, and emergent aspects of the whole situation.     

Cognitive neuroscience of actions: a whole is greater than the sum of its parts

The purpose of the present issue of Brain and Cognition is to demonstrate that the strength of neuroscience is in its multidisciplinary approach to understand events. Here we are concerned with the domain of action recognition and production. Seven articles have been selected as representative studies of actions carried out in different areas of neuroscience such as neuropsychology, neurophysiology, and cognitive science. Although each addresses different questions within the field, the articles share a common neuroscientific knowledge, as can be readily gathered from the references cited in each article.     

The whole is indeed more than the sum of its parts: perceptual averaging in the absence of individual item representation

We tested Ariely's (2001) proposal that the visual system represents the overall statistical properties of sets of objects against alternative accounts of rapid averaging involving sub-sampling strategies. In four experiments, observers could rapidly extract the mean size of a set of circles presented in an RSVP sequence, but could not reliably identify individual members. Experiment 1 contrasted performance on a member identification task with performance on a mean judgment task, and showed that the tasks could be dissociated based on whether the test probe was presented before or after the sequence, suggesting that member identification and mean judgment are subserved by different mechanisms. In Experiment 2, we confirmed that when given a choice between a probe corresponding to the mean size of the set and a foil corresponding to the mean of the smallest and largest items only, the former is preferred to the latter, even when observers are explicitly instructed to average only the smallest and largest items. Experiment 3 showed that a test item corresponding to the mean size of the set could be reliably discriminated from a foil but the largest item in the set, differing by an equivalent amount, could not. In Experiment 4, observers rejected test items dissimilar to the mean size of the set in a member identification task, favoring test items that corresponded to the mean of the set over items that were actually shown. These findings suggest that mean representation is accomplished without explicitly encoding individual items.     

When the whole is more than the sum of its parts: Group motivation gains in the wild

Whereas negative effects of groups on individual motivation have been reported for many years, recent research has begun to show when and why working in a group can produce motivation gains compared to individual work. So far, this evidence has been limited to laboratory settings and rather simple tasks. Using data from swimming competitions at the 2008 Olympics, evidence is presented that motivation gains in groups also occur in field settings with more complex tasks. Based on an instrumentality × value approach, we expect that late positions in a relay trigger motivation gains in groups due to an increase in perceived indispensability for the group outcome. This idea has been initially tested in a pilot study with competitive swimmers, demonstrating that perceived indispensability for the relay outcome indeed increases with later serial positions in a relay. Moreover, the main study with data from the 2008 Olympics revealed performance times consistent with this pattern of indispensability perceptions: while starting swimmers in the swimming relays performed at similar levels as in their individual competitions, swimmers at the later positions showed higher performance in the relay compared to their individual competition heats.     

Prior experience can influence whether the whole is different from the sum of its parts

In two conditioning experiments with humans, we found that participants’ prior experience exerted considerable influence on later learning of configural discrimination problems. Prior experience was manipulated by pre-training participants before the main acquisition stage. They either received a discrimination problem that encouraged an elemental solution (A+, B−, AB+, CD− in Experiment 1 and A+, AB+, C−, CB− in Experiment 2) or one that required a configural solution (AB+, BC−, CD+, DA− in Experiment 1 and A−, AB+, C+, CB− in Experiment 2). Then, all participants were shown a discrimination that required a configural solution (E+, F+, EF− in Experiment 1 and DE+, EF−, FG+, GD− in Experiment 2). In both experiments, participants who had received elemental pre-training were impaired on the later configural problem compared to participants who had received configural pre-training. The results suggest that organisms can flexibly process stimuli elementally or configurally.     

The whole is equal to the sum of its parts: a probabilistic model of grouping by proximity and similarity in regular patterns

The authors investigated whether the gestalt grouping principles can be quantified and whether the conjoint effects of two grouping principles operating at the same time on the same stimuli differ from the sum of their individual effects. After reviewing earlier attempts to discover how grouping principles interact, they developed a probabilistic model of grouping by proximity, which allows measurement of strength on a ratio scale. Then, in 3 experiments using dot lattices, they showed that the strength of the conjoint effect of 2 grouping principles--grouping by proximity and grouping by similarity--is equal to the sum of their separate effects. They propose a physiologically plausible model of this law.     

The sum of the parts does not equal the whole: evidence from bihemispheric processing.

The 5 experiments in this article examine whether bihemispheric processing can be predicted from the processing observed when information is directed initially to just 1 hemisphere. Ss decided if laterally presented words rhymed with a previously presented central target. Trials varied in the degree to which the information displayed was redundant. On some trials, the same word appeared twice; in others, different words appeared, but they both led to the same decision; and finally, on some trials, different words appeared, each of which also led to a different decision. The patterns found for unilateral and bilateral trials were distinct. Furthermore, the pattern observed on bilateral trials could not be predicted from that found on unilateral trials, suggesting that interhemispheric interaction cannot be surmised from observing a hemisphere processing information in relative isolation.     

Emotions help memory for faces: Role of whole and parts

The role of holistic or parts-based processing in face identification has been explored mostly with neutral faces. In the current study, we investigated the nature of processing (holistic vs. parts) in recognition memory for faces with emotional expressions. There were two phases in this experiment: learning phase and test phase. In the learning phase participants learned face–name associations of happy, neutral, and sad faces. The test phase consisted of a two-choice recognition test (whole face, eyes, or mouth) given either immediately or after a 24-hour delay. Results indicate that emotional faces were remembered better than neutral faces and performance was better with whole faces as compared to isolated parts. The performance in immediate and delayed recognition interacted with emotional information. Sad eyes and happy mouth were remembered better in the delayed recognition condition. These results suggest that in addition to holistic processing, specific parts–emotion combinations play a critical role in delayed recognition memory.     

When the event is more than the sum of its parts: 9-month-olds' long-term ordered recall

Research suggests that 9-month-old infants are able to recall single object-specific actions over delays of 24 hours. In the present research we investigated whether 9-month-olds are able to recall over more extended delays, and to recall the temporal order of events, as well as the individual actions in them. In addition, we investigated whether recall can be enhanced by pre- and/or re-exposure to target events. Using elicited imitation of novel, multi-step event sequences, we demonstrated that, as a group, 9-month-olds are able to recall target actions after delays of five weeks. However, after this long delay, only 45% of the infants recalled the temporal order of the events. Re-exposure to events during the delay interval proved necessary for boys, but not for girls; pre-exposure to events did not affect later recall. The implications of individual differences in infants' recall ability for the understanding of the development of the neural correlates of declarative memory are discussed.     

The logic of neuropsychological research and the problem of patient classification in aphasia

A critical analysis is presented of the assumptions that must be made to use the data from aphasia to constrain models of normal language processing. The implication of these assumptions for patient classification and research methodology in aphasia is considered.