Papers 61–67 Friday Morning 11:00–11:15 (61) Visual Acuity in Virtual and Real Depth. ANKE HUCKAUF, Bauhaus University, Weimar—Acuity, one of the basic visual functions, is known to be higher on the horizontal than on the vertical meridian (Rovamu & Virsu, 1979). We investigated visual acuity in depth and compared it with acuity in horizontal and vertical directions. Letters were presented tachistoscopically at 3º, 6º, and 9º of eccentricity in the left, upper, or backward visual field. Presentation was elicited by an accurate fixation. For depth acuity, a fixation arrow was placed at various distances between the monitor and the observer. Letter recognition was worse in depth than in both other directions, repeatedly and for all observers. However, the presentation of a virtual fixation arrow on an auto-stereoscopic monitor resulted in better performance than did the presentation of a real fixation arrow. This result demonstrates that accommodation can be controlled independently from vergence. However, an independent adjustment of accommodation and vergence does not seem to be under voluntary control. 11:20–11:35 (62) <strong>The</strong> Roles of Altitude and Fear in the Perception of Height. JEANINE K. STEFANUCCI & DENNIS R. PROFFITT, University of Virginia (read by Dennis R. Proffitt)—People often exhibit normative biases in their perception of the environment. For instance, slant is typically overestimated, and distance is usually underestimated. Surprisingly, the perception of height has rarely been studied. In a series of experiments, participants performed visual matching assessments of apparent distance and size while looking down from a balcony or looking up from the ground. When they were looking down, distances were overestimated by 60%, and the size of targets on the ground was overestimated by 22%. When they were looking up, the same distances were overestimated by 23%, and size estimates for targets viewed from below were accurate. In addition, a nonoptical variable—fear—was positively correlated with participants’ overestimation of height. We suggest that the overestimation of height that occurs when one looks down from a high place is due to both the altitude and a fear of falling. 11:40–11:55 (63) Color/Luminance Dissociations Across “How,” “What,” and “Where” Processing of Normal Participants: A Second Look. ALISSA WINK- LER, CHARLES E. WRIGHT, & CHARLES CHUBB, University of California, Irvine (read by Charles E. Wright)—In 2003, we reported that equiluminant color and isochromatic luminance defined stimuli that were found to be equisalient in a shape identification (“What”) task did not support equivalent performance in a pointing (“How”) task. Such task-related contrasts (TRCs) are consistent with the suggestion that there exist functionally separate pathways in the architecture of visual processing. Here, we report new experiments that (1) replicate our earlier finding of a TRC for color- and luminancedefined stimuli across the What and How tasks, eliminating methodological concerns, (2) reveal new TRCs between these tasks and an allocentric “Where” task, and (3) find no TRCs between speeded and information-limited variants of the What and Where tasks. Animal Learning Conference Rooms B&C, Friday Morning, 10:20–12:00 Chaired by Ralph R. Miller, SUNY, Binghamton 10:20–10:35 (64) Laws of Learning Appear to Differ for Elemental Cues and Compound Cues. RALPH R. MILLER & GONZALO P. URCELAY, SUNY, Binghamton, & KOUJI URUSHIHARA, Osaka Kyoiku University— <strong>The</strong> basic laws of learning for cues trained elementally have been intensively studied for a century. Recently, additional laws of learning have been identified for elements trained as part of compound cues, but researchers have assumed, without proper tests, that the laws governing elements alone also apply to elements within compounds. Experiments with rats will be reviewed demonstrating that interactions 10 between elements of compound cues not only produce the well documented phenomena of cue competition, but also, under certain circumstances, negate laws that apply to elemental cues alone. Examples of deleterious effects that do not always appear when target training occurs as part of a compound cue include trial massing, CS lengthening, latent inhibition, partial reinforcement, degraded contingency, and US preexposure effects. <strong>The</strong> addition of any one of these deleterious treatments to a preparation that otherwise yielded overshadowing reduced both the effect of the deleterious treatment and the overshadowing effect. <strong>The</strong> generality of these findings are discussed. 10:40–10:55 (65) Out of Sight, Not Out of Mind: Rats Know When an Absent Event Should Have Been Observed and When It Shouldn’t Have. AARON P. BLAISDELL, UCLA, MICHAEL WALDMANN, University of Göttingen, & W. DAVID STAHLMAN, UCLA—We previously failed to demonstrate second-order conditioning involving tone→light and light→food pairings in rats. When tested on the second-order tone alone, rats might have expected the light to occur upon termination of the tone. However, the light did not occur on tone-alone test trials, which may have reduced the expectation of food. We tested the hypothesis that occluding the light bulb at test, thereby removing the expectation that the light should be observable, would salvage the expectation of food at test. This hypothesis was confirmed by the demonstration of greater nosepoking to the tone, relative to an unpaired control stimulus, when the light bulb was occluded at test, but no difference in nosepoking when the light bulb was visible. Furthermore, the temporal location of the increased rate of nosepoking suggests that rats integrated a tone–food temporal map based on the tone–light and light–food temporal maps. 11:00–11:15 (66) Blocking and Pseudoblocking: New Control Experiments With Honeybees. P. A. COUVILLON, RACHEL E. BLASER, & M. E. BITTERMAN, University of Hawaii, Manoa—Prompted by doubts about the adequacy of the various control procedures long used in research on blocking, we repeated some earlier experiments with honeybees that had given the appearance of forward, concurrent, and backward blocking. <strong>The</strong> new experiments differed from the earlier ones only in that the target stimulus was omitted during the training and was encountered for the first time in the test. In the new experiments, just as in the earlier ones, the blocking groups responded less to the target stimulus than did the control groups. <strong>The</strong> results show that the effects of the different treatments of nontarget stimuli commonly compared in blocking experiments may generalize to the target stimulus and, thus, affect responding to that stimulus independently of experience with it. Implications for research on blocking in honeybees and other animals are considered. 11:20–11:35 (67) Delta–9-Tetrahydrocannabinol and Cannabinol, but not Ondansetron, Interfere With Conditioned Retching in the Suncus murinus: An Animal Model of Anticipatory Nausea and Vomiting. LINDA A. PARKER & MAGDALENA KWIATKOWSKA, Wilfrid Laurier University, & RAPHAEL MECHOULAM, Hebrew University of Jerusalem—Chemotherapy patients report not only acute nausea and vomiting during the treatment itself, but also anticipatory nausea and vomiting upon reexposure to the cues associated with the treatment. We present a model of anticipatory nausea based on the emetic reactions of the Suncus murinus (musk shrew). Following three pairings of a novel distinctive contextual cue with the emetic effects of an injection of lithium chloride, the context acquired the potential to elicit conditioned retching in the absence of the toxin. <strong>The</strong> expression of this conditioned retching reaction was completely suppressed by pretreatment with each of the principal cannabinoids found in marijuana, Δ9-tetrahydrocannabinol or cannabidiol, at a dose that did not suppress general activity. On the other hand, pretreatment with a dose of ondansetron (a 5-HT3 antagonist), which interferes with acute vomit-
Paper 68 Friday Morning ing in this species, did not suppress the expression of conditioned retching during reexposure to the lithium-paired context. <strong>The</strong>se results support anecdotal claims that marijuana, but not ondansetron, may suppress the expression of anticipatory nausea. 11:40–11:55 (68) Opioid Receptors and Individual Differences in Consummatory Successive Negative Contrast. SANTIAGO PELLEGRINI, MICHAEL WOOD, ALAN M. DANIEL, & MAURICIO R. PAPINI, Texas Christian University (read by Mauricio R. Papini)—Rats exposed to a downshift from 32% to 4% sucrose exhibit consummatory suppression, followed by recovery of normal behavioral levels, relative to 4% unshifted controls (consummatory successive negative contrast, cSNC). Previ- 11 ous research shows that opioid agonists (morphine, DPDPE) reduce the size of cSNC, whereas opioid antagonists (naloxone, naltrindole) enhance it. <strong>The</strong> recovery process involves emotional activation and conflict and is characterized by substantial individual differences. After a 32–4 downshift, rats (N = 40) were classified as exhibiting either fast recovery (resilience) or slow recovery (vulnerability) and were subsequently tested in an activity situation. <strong>The</strong> activity test was chosen as an independent measure of opioid sensitivity. Relative to saline controls, the nonspecific receptor antagonist naloxone (2 mg/kg) had a larger suppressing effect on activity in the slow-recovery than in the fast-recovery group. Individual differences in opioid receptors may determine whether rats exhibit resilience or vulnerability to the emotionally activating effects of cSNC.
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