The logic of ability,freedom and responsibility

The aim of this paper is to offer a rigorous explication of statements ascribing ability to agents and to develop the logic of such statements. A world is said to be feasible iff it is compatible with the actual past-and-present. W is a P-world iff W is feasible and P is true in W (where P is a proposition). P is a sufficient condition for Q iff every P world is a Q world. P is a necessary condition for Q iff Q is a sufficient condition forP. Each individual property S is shown to generate a rule for an agent X. X heeds S iff X makes all his future choices in accordance with S. (Note that X may heed S and yet fail to have it). S is a P-strategy for X iff X's heeding S together with P is a necessary and sufficient condition for X to have S. (P-strategies are thus rules which X is able to implement on the proviso P).Provisional opportunity: X has the opportunity to A provided P iff there is an S such that S is a P-strategy for X and X's implementing S is a sufficient condition for X's doing A. P is etiologically complete iff for every event E which P reports P also reports an etiological ancestry of E, and P is true. Categorical opportunity: X has the opportunity to A iff there is a P such that P is etiologically complete and X has the opportunity to A provided P. For X to have the ability to A there must not only be an appropriate strategy, but X must have a command of that strategy. X steadfastly intends A iff X intends A at every future moment at which his doing A is not yet inevitable. X has a command of S w.r.t. A and P iff X's steadfastly intending A together with P is a sufficient condition for X to implement S. Provisional ability: X can A provided P iff there is an S such that S is a P-strategy for X, X's implementing S is a sufficient condition for X's doing A, and X has a command of S w.r.t. A and P. Categorical ability: X can A iff there is a P such that P is etiologically complete and X can A provided P. X is free w.r.t. to A iff X can A and X can non- A. X is free iff there is an A such that X is free w.r.t. A.     

Recognizing faces in and out of context

Two experiments are reported which examined the influence of context on face recognition accuracy for novel and familiar faces respectively. Context was manipulated by varying the physical background against which the faces appeared. In Experiment I, 80 student subjects observed 18 faces before attempting to recognize them in a sequence of 36 al ternatives , For half the subj ects, the backgrounds changed from study to test, while for the remainder they stayed the same. In addition, for half the subjects, both the pose and expression of the face also changed, while for the others it remained constant. Changes in pose plus expression and context significantly reduced recognition accuracy for the target faces. Experiment 11 used an identical design, except that the faces of celebrities replaced the novel faces. The influence of context was eliminated but the effects of pose and expression were maintained. However, when only faces which were actually identified by subjects were considered, the effects of pose and expression, too, were eliminated. The significance of these findings for theories of contextual memory are discussed.     

Eye movement Responses of Repressors and Sensitizers to a stressful film

Groups scoring high, intermediate or low on the Byrne R-S Scale viewed an industrial accident film while horizontal eye movements were assessed by means of infrared corneal reflection. Neutral and stressful film segments were scored in terms of deviations from the center of the perceptual field (point of looking scores), and the standard deviations of these scores were calculated as an index of perceptual scanning. A stressful segment was also dichotically scored as to whether the point of looking was on or off dominant elements of the scene. Results indicated that Repressors and Sensitizers had equivalent levels of perceptual scanning (and both significantly higher than Intermediates' level) independent of film segment content, but that they differed in on/off and average point of looking for the stressful segment such that Repressors were avoiding stressful content. These data suggest that relatively high perceptual scanning can be an avoidant defensive style of attending to dynamic stimulus displays. The issue of adaptiveness of responding is considered.     

Short-term memory for spatial and temporal information

Two experiments examined the probed recall of visually presented letter sequences in which the items appeared at different spatial locations. Three types of probe were compared: (1) spatial position; (2) temporal association; and (3) combined position and association. In the first experiment, in which the spatial locations of the items were correlated with their temporal order, spatial probes were more effective than temporal association probes. In the second experiment spatial location was uncorrelated with temporal order, and spatial probes were less effective than temporal association probes. Regardless of the probe, errors tended to be items presented close in time to correct responses: spatial proximity was far less important. The results are discussed in terms of a storage system in which items and their spatial locations are organized within a temporal format. Both experiments showed superior combined probe performance, demonstrating that short-term retrieval is not limited to the use of one type of cue at a time. Secondary aspects of the results showed additionally that subjects can “edit” their responses to avoid making obvious mistakes, and that spatial location can be partially forgotten rather than being completely lost.     

Hemispheric specialization for speech opposed,by contralateral noise

Twenty right-handed Ss listened to a dichotic tape in which one of six consonant-vowel syllables was paired with a burst of white noise on each trial. Eight blocks of 40 trials were presented, with the syllables within a block presented to, the same ear. On each trial, Ss decided if/ ba/ was presented. Mean RT to right-ear items was 440.0 msec, while mean left-ear RT was 453.6 msec. Responses indicating the presence of /ba/ were made significantly more quickly than responses indicating its absence, with no significant interaction of ear and type of decision. This study demonstrated a right-ear advantage in the perception of spoken syllables when noise is presented to the opposite ear. An interpretation of the RT differences between ears in terms of callosal transmission time is discussed, and implications of this study for the perceptual origins of the ear advantage effect are considered.     

Are two heads better than one? Experimental investigations of the social facilitation of memory

The hypothesis that two people collaborating in recall would remember more than a single person was examined in a series of four experiments. All the experiments used variations on the same ‘sequential’ design where, in social conditions, people recalled alone initially and then recalled jointly in pairs: as a control for reminiscence, some people recalled alone on two separate occasions. On the second recall in all of the experiments two people always recalled more than one, but this was simply due to the independent statistical summation of two people's memories: no evidence whatsoever was found for the pairs of people generating new information that was not available to either member of the pair. This surprising result was not attributable to artefacts linked to the complexity or familiarity of stimulus material, nor was it linked to variations in people's cognitive perspectives. No evidence of social facilitation of memories was therefore found: two people recalling together certainly pool their separate memories so as to outperform individuals but the social interaction does not appear to generate previously unavailable memories.     

Who remembers best? Individual differences in memory for events that occurred in a science museum

Individual differences in memory and suggestibility were assessed in an experiment involving 1989 people who attended the Exploratorium, a science museum located in San Francisco. Subjects watched a brief film clip of an assault and later answered questions about it. Approximately half received misinformation about some critical items. Four demographic variables (gender, educational level, age, and occupation) were examined to determine their impact on memory performance. The principle of discrepancy detection predicts that, compared to individuals with a good memory, people who have poor memory to begin with will be relatively suggestible (that is susceptible to misinformation). Some of our findings were consistent with this principle. For example, children (5–10 years) and elderly (over 65) were relatively inaccurate and also relatively suggestible. Other findings were not consistent with the principle, for example the finding that artists and architects were relatively accurate, but they were also highly suggestible.