DOES PACKAGE SIZE MATTER? A UNIT-PRICE ANALYSIS OF “DEMAND” FOR FOOD IN BABOONS

In a study examining “demand” for food, responding of 8 adult male baboons (Papio c. anubis) was maintained under a fixed-ratio schedule of food reinforcement during daily 23-hr experimental sessions. Completion of the ratio requirement resulted in the delivery of one, five, or 10 1-g food pellets. Supplemental feeding was limited to fruit and a dog biscuit daily. Responding increased as “cost” was increased across a wide range of fixed-ratio values before reaching a maximum and then decreasing. Increasing the number of food pellets per delivery decreased total responding and the number of reinforcements per day. A unit-price analysis, in which intake was converted to grams per day and fixed-ratio values were converted to responses per gram, yielded demand functions that overlapped at lower unit prices. Under one or more multiple-pellet conditions, however, intake decreased more quickly than under the one-pellet condition as the fixed-ratio value was increased in all but 1 baboon. This indicates that even when using unit-price conversions, there was variability in total intake. Although unit-price conversions yielded intake data that were more consistent across conditions, conditions differed in response topography even at the same unit prices: Under the multiple-pellet conditions there were longer pauses in responding, running response rate was slower, and the first eating bout (i.e., “meal”) of the session was smaller than under the one-pellet condition. These findings (a) support the heuristic value of a unit-price analysis for studying responding for and consumption of commodities that have similar attributes, and (b) indicate that different response topographies may result in similar intakes of a commodity.     

The Preference for Pointing With the Hand Is Not Universal

Pointing is a cornerstone of human communication, but does it take the same form in all cultures? Manual pointing with the index finger appears to be used universally, and it is often assumed to be universally preferred over other forms. Non‐manual pointing with the head and face has also been widely attested, but it is usually considered of marginal significance, both empirically and theoretically. Here, we challenge this assumed marginality. Using a novel communication task, we investigated pointing preferences in the Yupno of Papua New Guinea and in U.S. undergraduates. Speakers in both groups pointed at similar rates, but form preferences differed starkly: The Yupno participants used non‐manual pointing (nose‐ and head‐pointing) numerically more often than manual pointing, whereas the U.S. participants stuck unwaveringly to index‐finger pointing. The findings raise questions about why groups differ in their pointing preferences and, more broadly, about why humans communicate in the ways they do.     

THE BACON not the bacon: how children and adults understand accented and unaccented noun phrases

Two eye-tracking experiments examine whether adults and 4- and 5-year-old children use the presence or absence of accenting to guide their interpretation of noun phrases (e.g., the bacon) with respect to the discourse context. Unaccented nouns tend to refer to contextually accessible referents, while accented variants tend to be used for less accessible entities. Experiment 1 confirms that accenting is informative for adults, who show a bias toward previously-mentioned objects beginning 300 ms after the onset of unaccented nouns and pronouns. But contrary to findings in the literature, accented words produced no observable bias. In Experiment 2, 4 and 5 year olds were also biased toward previously-mentioned objects with unaccented nouns and pronouns. This builds on findings of limits on children's on-line reference comprehension [Arnold, J. E., Brown-Schmidt, S., & Trueswell, J. C. (2007). Children's use of gender and order-of-mention during pronoun comprehension. Language and Cognitive Processes], showing that children's interpretation of unaccented nouns and pronouns is constrained in contexts with one single highly accessible object.     

Gavagai again

Quine (1960, Word and object. Cambridge, Mass.:MIT Press, ch. 2) claims that there are a variety of equally good schemes for translating or interpreting ordinary talk. ‘Rabbit’ might be taken to divide its reference over rabbits, over temporal slices of rabbits, or undetached parts of rabbits, without significantly affecting which sentences get classified as true and which as false. This is the basis of his famous ‘argument from below’ to the conclusion that there can be no fact of the matter as to how reference is to be divided. Putative counterexamples to Quine’s claim have been put forward in the past (see especially Evans 1975; 1975, Journal of Philosophy, LXXII(13), 343–362. Reprinted in McDowell (Ed.), Gareth Evans: Collected papers. Oxford: Clarendon Press.), and various patches have been suggested (e.g. Wright (1997, The indeterminacy of translation. In C. Wright & B. Hale (Eds.), A companion to the philosophy of language (pp. 397–426). Oxford: Blackwell)). One lacuna in this literature is that one does not find any detailed presentation of what exactly these interpretations are supposed to be. Drawing on contemporary literature on persistence, the present paper sets out detailed semantic treatments for fragments of English, whereby predicates such as ‘rabbit’ divide their reference over four-dimensional continuants (Quine’s rabbits), instantaneous temporal slices of those continuants (Quine’s rabbit-slices) and the simple elements which compose those slices (undetached rabbit parts) respectively. Once we have the systematic interpretations on the table, we can get to work evaluating them.     

Isolating observer-based reference directions in human spatial memory: head, body, and the self-to-array axis

Several lines of research have suggested the importance of egocentric reference systems for determining how the spatial properties of one's environment are mentally organized. Yet relatively little is known about the bases for egocentric reference systems in human spatial memory. In three experiments, we examine the relative importance of observer-based reference directions in human memory by controlling the orientation of head and body during acquisition. Experiment 1 suggests that spatial memory is organized by a head-aligned reference direction; however, Experiment 2 shows that a body-aligned reference direction can be more influential than a head-aligned direction when the axis defined by the relative positions of the observer and the learned environment (the "self-to-array" axis) is properly controlled. A third experiment shows that the self-to-array axis is distinct from - and can dominate - retina, head, and body-based egocentric reference systems.     

Keep making sense

In a number works Jerry Fodor has defended a reductive, causal and referential theory of cognitive content. I argue against this, defending a quasi-Fregean notion of cognitive content, and arguing also that the cognitive content of non-singular concepts is narrow, rather than wide.     

How suboptimal is suboptimal choice?

In a frequently used suboptimal‐choice procedure pigeons choose between an alternative that delivers three food pellets with p = 1.0 and an alternative that delivers ten pellets with p = 0.2. Because pigeons reliably choose the probabilistic (suboptimal) alternative, the procedure has been proposed as a nonhuman analog of human gambling. The present experiments were conducted to evaluate two potential threats to the validity of this procedure. Experiments 1 and 2 evaluated if pigeons obtained food at a lower unit price (i.e., pecks per pellet) on the suboptimal alternative than on the optimal alternative. When pigeons worked under this suboptimal procedure they all preferred the suboptimal alternative despite some pigeons paying a higher price for food on that alternative. In Experiment 2, when the unit price ratio more closely approximated the inverse of the expected value ratio, pigeons continued to prefer the suboptimal alternative despite its economic suboptimality. Experiment 3 evaluated if, in accord with the string‐theory of gambling, the valuation of the suboptimal alternative was increased when pigeons misattributed a subset of the suboptimal no‐food trials to the optimal alternative. When trial sequences were arranged to minimize these possible attribution errors, pigeons still preferred the suboptimal alternative. These data remove two threats to the validity of the suboptimal choice procedure; threats that would have suggested that suboptimal choice reflects economic maximization.     

Communicative functions of directional verbal probabilities: Speaker’s choice,listener’s inference,and reference points

Verbal probabilities have directional communicative functions, and most can be categorized as positive (e.g., “it is likely”) or negative (e.g., “it is doubtful”). We examined the communicative functions of verbal probabilities based on the reference point hypothesis According to this hypothesis, listeners are sensitive to and can infer a speaker’s reference points based on the speaker’s selected directionality. In four experiments (two of which examined speakers’ choice of directionality and two of which examined listeners’ inferences about a speaker’s reference point), we found that listeners could make inferences about speakers’ reference points based on the stated directionality of verbal probability. Thus, the directionality of verbal probabilities serves the communicative function of conveying information about a speaker’s reference point.     

The effect of information overlap on communication effectiveness

It makes sense that the more information people share, the better they communicate. To evaluate the effect of knowledge overlap on the effectiveness of communication, participants played a communication game where the "director" identified objects to the "addressee". Pairs either shared information about most objects' names (high overlap), or about the minority of objects' names (low overlap). We found that high-overlap directors tended to use more names than low overlap directors. High overlap directors also used more names with objects whose names only they knew, thereby confusing their addressees more often than low-overlap directors. We conclude that while sharing more knowledge can be beneficial to communication overall, it can cause communication to be locally ineffective. Sharing more information reduces communication effectiveness precisely when there is an opportunity to inform-when people communicate information only they themselves know.     

产品销量和推荐数对网络消费决策的影响:价格的调节效应

基于目标感染理论,探究了产品销量和产品推荐数对大学生网络消费决策的影响,并进一步探究了产品价格在大学生网络消费决策中的调节作用。两项研究均表明,产品销量和推荐数均会促进大学生做出消费决策。其中,产品价格调节了两者对网络消费决策的影响,具体表现为在选购低价格产品时,大学生更加看重产品销量,倾向选购高销量产品;而在选购中高价格产品时,大学生更加看重产品推荐数,选购高推荐数的产品。本研究为网络电商平台如何针对不同价位产品制定产品展示方案提供了理论支持和实践指导。